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Discussion Starter #21 (Edited)
Ok so it's 2 stroke oil in the crank housing, sure of it. I had (have) the oil that the previous guy used and compared, same stuff. Sooooo, not going to split the cases. Wooohooo!
 

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Your piston appears to have little to no wear on it. Is the piston broken on the other side?

First diagnoses is that, the piston was too tight & started to scuff. At the same time it looks broken on the back side?
Maybe the shop who worked on the cylinder missed with their measurements. It’s common & very easy to hone the cylinders improperly. If the hone is too tight, it follows the easiest way thru the cylinder & the bore turns out egg shaped. If this happened the bore measurements could be OK but the cylinder isn’t Round & Straight.

As the others have noted; if a thrust washer broke, this may have been the whole problem.

You also don’t just drop the sleeve; they must be cut out. Most times with your type of cylinder we weld around the base gasket area so the new sleeve can be somewhat thinner.

I’m reading on page 2 that you’ve got a 70mm liner installed. This may or may not be a problem, time will tell.
You probably have some canned type of 70mm sleeve, who knows, there are only 3 production sleeve manufacturers.
 

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85- 86 lt250s' have a bore of 70mm. and a stroke of 120mm. So that's a factory cylinder.

As for the pic. looking like a piece of piston missing on the back part of the image, they have a cut-out and that is the "twisted style" piston that I mentioned in another post. John, you have discussed that type of piston on I believe ? on marine motors that you have encountered.

The scuffling may be to 2 things.. not the proper oil ratio mix or just running that thing balls out full throttle for an extended period of time like down a road and the piston heated up causing the oil to breakdown.
 

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There are certainly a lot of ideas of what’s happening & what causes it. It’s easy to tell who’s the most knowledgeable about your type of machine.
My work is focused on small engine cylinders & no particular brand. I don’t keep track of years & bore sizes. When I’m asked about performance port work; I usually tell the customer to find somebody who specializes in this kind of equipment & is frequently seen at local racing events. I’ll bet that mgty3whlr is one of those special people to see about porting & such for this kind of machine.

When a customer brings by a problem cylinder; my first step is to measure the cylinder for size, is it Round & Straight. What quality of tools serviced the cylinder; was a simple Egg Beater type of hone used. The longer you own your machine, the more you need to learn & know. If you work with a quality builder, never hesitate to ask questions about your equipment.
E2S is a good sounding board to start building your knowledge.
:thumbsup:
 

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Discussion Starter #25
The cylinder was absolutely re-sleeved. Didn't notice this myself but the guy I took it to pointed out that the old sleeve was still in there, a new one was "pressed" in and the bore wasn't exactly 70mm it was off by .3 but the piston is 70mm. The marks/smears on the piston are seize marks which were already there when I got the 250 and it's a Wiseco piston from a rebuild likely many many years ago. In any event the cylinder and piston will be a non issue shortly.

There's a possibility, after inspecting the inside of the crank housing, that at some point the thrust washers did break apart and get into the crank area because I can see little divits and gouges in there (maybe just normal manufacturing issues?). However the thrust washers that fell into the crank housing while I was removing the piston are in fine shape and if I can't source some aluminium versions I'll probably just reuse them. Tried Quadracer HQ and their out of the washers. I'll try calling the place mentioned in this thread to see if they still make/sell the aluminium washers.

I took the stator cover off yesterday and I've got quite a bit of white corrosion build up on the "bell" housing and the crank rod nut is quite rusty, took a pic and I'll get that posted here in a little bit to get some opinions on this white corrosion. Also took the water pump cover off and my impeller is in perfect condition. Next I'm gonna take the clutch cover off and make sure my counter balance is timed correctly and that the gears are all in good shape.

Thanks again peeps, id be lost without E2S. :thumbsup:
 

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Discussion Starter #26
Have the piston in my hands right now. It's a stock Wiseco piston (compared to pics) however I've just found out that the last four digits on the dome are it's measurements and it's a 70.25mm piston not 70mm. Regardless, will soon have it bored to 71mm with matched piston.

Since the bike's been in my possession I never had it much (if at all) above 3/4 throttle or keept it revving that high for more than a few seconds. Haven't been able to get it out into wide open spaces to go balls out yet (lol). That said I have on more than a few occasions gotten to 5th gear 3/4 throttle pretty quick. Last time out I was making carb adjustments in an attempt to address a loss of power (bogging and stumbling = to rich right?) at about half throttle and ran out of gas (upper portion of tank) just as I got it dialed in. Switched to the reserve position on the petcock dial and all hell broke loose with a shit ton of white smoke. Fuel/oil ration it was using, 32/1 (I was told) with Lucas semi-synthetic which as far as I know is some good stuff and I have the bottles previous owner had purchased.

I've since removed all the gas (motor sitting on bench at the moment) and will also remove the petcock to check it's filters and get any remaining gas out of the tank and I'm gonna use probably 25/1 ratio in my next mix. Factory mix suggested is 20/1 but that seems excessive to me with modern oils, what's your guys take on that? What ratio, using Lucas oil, would you suggest?
 

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I don't normally drone on about things but this bears repeating because it's important and I really don't want to see you trash your new engine. DO NOT put that engine together with the oem washers. This guy was also in a hurry and didn't listen to several people that warned him: http://forums.everything2stroke.com/threads/45925-thrust-washers-again? You've been warned, lol.

Same thing with a leak tester. If you don't leak test an engine after putting it together you are asking for problems. All it takes is one air leak to lean out your mixture and seize your engine within minutes. You can probably build a simple one for $20. The only thing you might have to order is a low pressure gauge like this one: http://www.amazon.com/Winters-Economy-Pressure-Display-Accuracy/dp/B0087UBDAQ/ref=sr_1_5?ie=UTF8&qid=1444495004&sr=8-5&keywords=low+pressure+gauge Other than that all you need is an expandable plug to plug off the exhaust and you can build the tester out of pvc pipe that will fit inside your intake. Cap the other end of it and drill two holes, one to screw the gauge into and one to put a tire valve into. Pump up the engine with a bicycle tire pump and it should hold 5 or 6 psi for 5 minutes.

I wouldn't worry too much about a little 2 stroke oil in the crankcase.
 

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Discussion Starter #28
Here's the pic of the stator bell thing...lol.

IMG_1818.JPG

Always have to resize the image to get to 2mb...

To me it looks like a slightly corroded car battery terminal post with that white dust on the bell. What's your opinion on this and how the hell do I remove the bell without putting the engine in a vise to get enough torque on the nut? For the record, I would never put the engine in a vise...Probably have to use some liquid wrench on the nut.

Ohh right, I was also able to get the stator cover off (remember stripped screws?) just used a center punch to wake up the screws and a much bigger phillips head, screws came right out, a bit over torqued though in my estimation. Took ~50lbs to bring em out and I believe the factory spec is ~half that (found a manual : ).

I love working on this little engine and people need to keep in mind (ehemmm previous owner) they are little and over torquing a little engines nuts and bolts can cause major f-ing issues for its next owner...anti-seize. Also, don't drown in lock-tight and never use red only a dab of blue. Gonna have to go around and clean out all of the threads. I'm not sure but I don't think anyone ever came back on the stainless nuts bolts and screws I stumbled on. Anyone out there use aftermarket stainless screws? Ti exist? Hardware store likely carry acceptable replacements? I only have the service manual at this point not the Clymer yet and I don't think it mentions the measurements on each screw nut and bolt, Clymer have this info?
 

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Not familiar with Lucas oil but any modern oil should be good at 32:1. I wouldn't change the ratio. One other thing to remember, by adding more oil you are actually leaning your mixture. More oil = less gas = leaner mixture. A lot of guys like Maxima Castor 927 at 32:1 if you're looking for something proven.
 

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Doesn't look like a big deal to me, just a little corrosion. I would clean the spot on the side where it comes around and energizes the pick up coil. If you want to remove the flywheel you need one of these (always good to have around anyways) http://www.ebay.com/itm/Motion-Pro-08-0026-Flywheel-Puller-Suzuki-LT-250R-Quadracer-1985-1990-/311407964967?hash=item48815c7327&vxp=mtr

I have the stainless bolts on my zilla and like them but I've seen other people complain that they don't play well with the aluminum and seize.
 

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John,
If you are still following this thread you should really consider making up a bunch of those aluminum washers and selling them on the site. From what I've seen before they're just 7075 in most cases, not some fancy alloy or something. They seem to be getting hard to find, I've looked twice on ebay for them in the past few weeks and nobody is selling them. Used to be several sources just on ebay.
 

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70.25 Wiesco piston; now we’re getting somewhere. Your cylinder has been bored +.010” or +.25mm, whichever you like. Some people I work with only use metric’s which can really get confusing.
Anyway; if the cylinder needs a bore, think about the minimum you can get by with. Wiesco’s next oversize for your piston is a 70.50mm or +.020”. Regardless, will soon have it bored to 71mm with matched piston. Most of us only bore enough out to clean the cylinder up; Your lucky that Wiesco is starting to produce pistons in .25mm or +.010” increments. With a +.010” piston I seldom bore but use a precision hone instead. There’s no reason to bore out any more than necessary. You should also be aware of what the maximum oversize piston which Wiesco makes for your engine. They usually go to +2mm for each brand of engine. (Always check the ring end gap) when assembling.

The other guy’s know more about your fuel situation but maybe; turn your tank upside down & dump it out & start over with a fresh load of fuel

I’m sorry for the Rant; Wiesco makes the best piston, but be aware every brand has it’s peculiarities.

JT
:NodYes:
 

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Discussion Starter #33
Ok so I've done some more research and came across this amazing thread (Jerry Hall wisdom). Hopefully there's no legality issues with linking to this thread on this forum.... http://z15.invisionfree.com/LT250_LT500HQ/index.php?showtopic=4146 Great stuff

In the thread I linked to Jerry talks about plastic washers (?). Likely hardened polly plastic. Is he referring to the thrust washers? See below.

"Why does the LT 500 Suzuki have problems with the bearing pockets wearing out? Our first guess was that the main bearing pockets were loose on the new engines. We started measuring the bearing pockets on new cases and found that Suzuki was setting the interference fit between the main bearing and the bearing pocket where it should have been. Our next observation was the problem seemed to appear on the “stockish” type engines that had a million miles on them or on the race engines. We began to see other problems, broken crank pins, and broken crankshafts on the ignition side at the junction of the main bearing shaft and crank web. We began to study the failures and the failures pointed to the cause of the problem. Before a part breaks, it has to flex. The flex leads to fatigue and the part will eventually crack and break in the fatigued area.


Crankshaft flexing is what wears out the bearing pockets. The majority of the flex occurs in the crank pin. Another area of flex is at the junction of the main bearing shaft and the crank web. How do we know that these areas flex? These are the two areas where the crankshaft breaks.

What causes flex? The two major factors that contribute to the flex of any crankshaft are high rpm and the load that the connecting rod exerts on the crank pin when the engine is under full power.

The connecting rod is experiencing high tension as the piston approaches top dead center, when the engine is at high rpm and the throttle is closed,. The piston is pulling on the connecting rod with a force of thousands of pounds. As the rpm is increased this force increases exponentially. This force causes the crank pin to flex so that the distance between the crank webs DECREASE in the area opposite the crank pin.

When the engine is under power, the piston exerts force on the connecting rod and the rod transmits this force to the crank pin. The peak pressure on the piston occurs in the neighborhood of 20 to 30 degrees after top dead center. When the power level of the engine is increased, the crank flexing force increases. The force on the crank pin when the engine is under power causes the crank pin to flex so that the distance between the crank webs INCREASE in the area opposite the crank pin.

The flex in the crank pin is not visible, but it exists on a micro level. For discussion purposes the main bearings should be thought of as being part of the crank webs. Looking at the motion of the crank webs described in the above paragraphs, we can easily observe the motion of the main bearings. The interference fit between the main bearings and the bearing pockets helps resists some of the motion of the bearings, but some movement of the bearing will occur when the crank pin flex exceeds a certain level.

The friction and extreme pressure between the outside of the main bearing and the bearing pocket causes micro welding to occur between the two surfaces when they are both iron based materials. The micro welding is what causes the pits to occur on these surfaces.

How can we prevent the problems described above?

One obvious solution would be to increase the diameter of the crank pin. Increasing the crank pin diameter would require an increase in the outside diameter of the crank webs if we are to maintain a reliable design. The proper interference fit between the crank pin and the crank web must be maintained in order to prevent movement between the web and the crank pin. I have never seen a stock LT500 crank web split between the crank pin hole and the outside diameter of the crank web. I have seen the crank webs split between the crank pin holes and the outside diameter of the crank web when the correct interference fit on the crank pin is used on stroker cranks. There is not adequate strength between the crank pin holes in the web without increasing the OD of the web. Welding the crank pins to the existing webs should not be considered as an option. Welding crank pins to the webs are just band-aids for a poor design or loose crank pin holes. A large diameter crank pin is also not desirable for high-rpm two strokes due to the increased moment of inertia of the bearing cage assembly and the pre-mix type of lubrication system

Another solution would be to run two main bearings on each end of the crank. This is not an affordable solution because it would require a new crankcase and crankshaft design.

We started seeing bearing pocket failures on the 1987 race engines before the 1988 models were released. The LT 500 engine was designed for power levels in the 40 hp to 50 hp range and engine speeds of around 6500 rpm. We often spin these engines over 8000 rpm and we can easily produce power levels in excess of 80 HP. The bearings are going to move in the bearing pockets when we elevate the power and rpm. So what is the best cost based solution?


We re-sleeved the early pocket failures with steel inserts on the first race engines. They did not seem to last much longer than a new set of cases that had cast iron inserts. The steel inserts would eventually get loose and had the pitting problem like the cast iron inserts. We used brass inserts and then silicon bronze. The bronze seemed to last longer but eventually wear out. The bronze did not show any pits when they got loose like the iron bases inserts. We also tried aluminum inserts and they eventually got loose without pitting. We eventually came to the conclusion that the main bearings are going to move in the bearing pocket. What can we use as material between the bearing and the cases that will minimize the wear? We tried using plastic for an insert material and watched these engines for a few years on different customer engines. Upon teardown the bearing pockets and the outside of the main bearings did not show any ware. We have used the plastic inserts in hundreds of main bearing pockets over the last 20 years in the LT500 engines.

I do not believe that there are any “cushioning” effects on the bearings as a result of the plastic inserts. I do not believe that there is any other magical properties of the plastic inserts other than it does not ware as fast as the metal inserts.

Jerry"
 

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Discussion Starter #34
Ok so Jerry is talking about the crank shaft bearings and associated sleeves they ride in. Could the same methodology be applied to the thrust washers? I realize the thrust washers experience higher temps but I believe polymers are made that withstand higher temps and aren't terribly hard to come by. Not to say that the aluminium is hard to come by either but maybe a poly replacement would be better?
 

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I just spent the last hour going thru Jerry Hall’s thread, he really knows his stuff. It’s nice to know that another pro has the same opinions about cylinder liners as myself. One thing that Jerry has overlooked about plated cylinders; the cost to manufacture is far less than inserting an iron sleeve. I’m sure that the economics has much to do with this conversion.
 

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Discussion Starter #36
Heh, doesn't seem to be ranting to me. Appreciate the feedback, my brain is a sponge. OK, so the gentleman who's doing this cylinder work for me (if I had access to his tools id do it myself), after taking a look at the sleeve and grooves said we might have to go to 71mm, took a look at his catalog and wrote some things down (lol), quoted me a price. I picked his brain a bit and he's (I believe) quite well known, putting 2 and 2 together. Joe's been at this for 30+ years and his machine shop is well equipped (jealous...yeah a little bit lol). As I had said hopefully me and this dude build a good rapport and if when the works's complete and all is copacetic I'll drop his contact info here on the forums. Hell, some of you may already have his contact info. Seems Joe knows his way around a motorsports engine, can do frame work, modify A arms (make stock arms adjustable), extend swing arms.....won't rebuild a nitrogen shock though lol.

I've done some more thinking, do that a lot, and I've come to a conclusion, admittedly I've flip flopped on this...Had said I wanted to get her into riding shape again stat, and I do more than anything, but I think what I'll do is get the engine back together, give her a couple rips, take the engine back out and proceed to strip the frame. The frame needs gussets, it is a steel frame right? I can do that work myself and I'll feel better about the frame strength. I don't have access to a CNC quality machine at work though so making the thrust washers isn't an option. There are quite a few places here that do that sort of work and have a precision machine though so i will look into that for myself and hopefully (maybe) fellow quadracer's. I mig weld (taught myself with a fair amount of help from the other guys, still much to learn) why I asked about the frame material. No tig experience yet...

So the frame, still the lightest atv frame for a 250? Just don't recall if its a steel frame, nerf bars are steel, already awaiting a new coat of paint. Anyways I plan on riding fairly hard, not going moto cross but I'm not afraid of a jump either, or a drag race for that matter, or a trail race lol (neighborhood riding to a limited degree hehe). IS frame failure from jumps common? Are those dents supposed to be in the frame on the right side of the engine space? Seemed the dents helped me access the bolts/mount on the bottom of the engine, that why their there? And while we're talking about the chassis, I could swear I've got more positive camber on the front right than on the left and then sometimes not. What's the best way to be sure the camber is equal? Frame looks straight and I'm gonna measure it as best I can to see if distances are at least equal.

Lot's to do...but I dig it. Feel like a mad scientist lol. So frame's getting sand blasted and repainted. OR, is it possible sand blast and just "seal it" and leave naked? What can I say I like 'em naked...

Ok feeling like a FaceBook junkie, thanks guy. :Grin:
 

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Discussion Starter #37
Just can't stay away. From the Jerry thread "If you decide to use a piece of hose on the HPR 19 pipes, continue to use the heavy spring that holds the pipe stinger and silencer together at their junction. The spring is essential to balance the loads on the pipe and silencer mounts." I've got an old -Full FMF Fatty Gold- and mine is broken at the interface he mentions (realize he isn't talking about the same pipe but still). I've yet to look but do the FMF's typically have some sort of spring tension system here holding the mid-pipe to the silencer? When I say mine is broken, it's a source of an exhaust leak and it looks like a piece was broken off of the mid-pipe which may have been a flange. The other end of the mid-pipe connecting to the "fatty" has a rubber sleeve with springs, don't know if that's factory but its doing it's job. The entire exhaust of course is slip-fit and at the exhaust port on the cylinder, beyond a single spring there's nothing else securing the pipe to the flange. Seems like a flange of some sort on the pipe between the flange and exhaust port would be ideal. Or is it just a secure as best you can (hope it stays put) sort of situation?

Ok I'm really done this time (for a bit) GF's off to a girls night out camping trip and I need to get the front plastics back off and tend to the organized chaos that is my garage at the moment.

:NodYes:
 

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Jerry is who I told you to contact to get the aluminum washers (Halls Precision Racing) so if there were some benefit to making them out of plastic he would be doing it. Only thing I've seen on an FMF (that I remember) is the rubber sleeve between the two sections. Someone is usually selling one of those FMF's on ebay, go there and look at the pictures to see if you are missing anything on the cylinder end. Yes, the frame is just steel and it's pretty thin. I've seen guys gusset them before but they used a tig.
 

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Discussion Starter #39
Right found that out shortly after my post, lol hadn't put those 2 names together initially. Sure you can tig weld steel just personally don't yet have any experience with tig (yet). Mig with aluminium, heard it's a pita. Know I can mig weld it though being steel. Just gonna strip it down to the frame and get the multiple layers of paint off it. Make sure there aren't any cracks and add the gussets. A shame no one is supplying frames anymore, least not that I could find. If only I had more time available for personal stuff at work, i could make a frame. Even with the dents this frame will do, all seems straight as far as I could tell going over it tonight.

Tempted to complete the strip down process tomorrow and take the frame to work Monday LOL. Your advice on waiting till spring to ride her again keeps ringing in my head. What to do what to do....I guess I'll know when I know, ya know?

:Cheers:
 

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Any of you folks who are yearning to learn more about welding; Enroll in a TIG-MIG welding class at your local community college. Years ago when I bought my first wire welder which is still going strong after some forty years, I took the class at the night school program. For a few dollars & a lot of new friends, go for it, you won’t be disappointed.
 
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