Rm 500

[JohnnyO]

excuse the ignorance but why the transplant - weren't the 250 and 500 frames very similar anyway for this/these years?  What would be consider an advantage of doing this?

cheers

Rossco

I'm wondering the same myself!? An air cooled 500 into an aircooled 250 frame? Why.  Maybe a bit of weight saving but I'd imagine they put that extra weight into the 500 frame for a reason.......

The frames are totally different. It's an aircooled 500 into a watercooled '84 250 frame which got a lot of changes while the 500 frame remained the same from '81-'85.

[cloggy]

I remember reading about the 250/500 back in the day. I think the 250 frame had had a bit more tweaking over the years and subsequently was a little better on the track.
Why anyone would bother watercooling a 500 is beyond me. The engine never got any developement simply because everyone said that it always had plenty  of power

[Hoony]

with a water cooled 500 there is less vibration

[oldfart]

And they are still make kits for them.   ( water cooled )

[zorroz]

The problem with the LT500 engine is the housing area that holds the crank bearings in is alloy and fails quickly. In usa they modify them with a steel sleeve and never have a problem again.

I have been collecting part for my rm500e for the last 5 years and must say parts a thin on ebay usa. There is hardly ever any parts listed. I always thought they were dime a dozen. Yet lots of RM400 parts.

[Marc.com]

I have been collecting part for my rm500e for the last 5 years and must say parts a thin on ebay usa. There is hardly ever any parts listed. 

Maybe it is because more of the RM500s are still running. But you are right none seem to have been parted out in a long time on ebay.

[BAHNZY]

Zorroz is 100% on the money.
The bottom end (by today’s standards) is poorly engineered. With the torque and HP that these engines put out combined with a quad configuration where there is a lot more stress and strain on the engine, the main bearing location points go out of shape and eventually the main bearing spins in the housing, the crank goes out of alignment and the bottom end fails, generally in a catastrophic way. If you have an engine that has not got to that point, I was advised by those with experience that it is only a matter of time before it does. There is a few machine shops in the good old US of A that have jigs made up that line bore the cases & fit steel inserts for the bearings. They then balance the crank, which has to be done with a new rod and piston and you are good to go. By the time they supply the piston, rod, do the machine work and balance the crank it typically runs at about $1500 USD. Add to that a gasket kit, seals and bearings and the cost of buying the engine in the 1st place and you can see the $ quickly add up. Search the forums and you will quickly find this information.

I was also informed that if the water pump system is worn out and/or corroded, which is not unusual, then expect a further $500 for the bits to get it sorted. This does not surprise me as the water pump bearings, oil seal and the mechanical seal for my 84 RM125 project were more than $200, at a good price!

Firko, I sold the engine (which needed the above main bearing work) to a guy in Newcastle who is a die hard LTR fan. He told me that he only rides it at Stockton and reckons it the fastest thing there, not that I cared to much.

[All Things 414]

Zorroz is 100% on the money.
The bottom end (by today’s standards) is poorly engineered. With the torque and HP that these engines put out combined with a quad configuration where there is a lot more stress and strain on the engine, the main bearing location points go out of shape and eventually the main bearing spins in the housing, the crank goes out of alignment and the bottom end fails, generally in a catastrophic way. If you have an engine that has not got to that point, I was advised by those with experience that it is only a matter of time before it does. There is a few machine shops in the good old US of A that have jigs made up that line bore the cases & fit steel inserts for the bearings. They then balance the crank, which has to be done with a new rod and piston and you are good to go. By the time they supply the piston, rod, do the machine work and balance the crank it typically runs at about $1500 USD. Add to that a gasket kit, seals and bearings and the cost of buying the engine in the 1st place and you can see the $ quickly add up. Search the forums and you will quickly find this information.

I was also informed that if the water pump system is worn out and/or corroded, which is not unusual, then expect a further $500 for the bits to get it sorted. This does not surprise me as the water pump bearings, oil seal and the mechanical seal for my 84 RM125 project were more than $200, at a good price!

Firko, I sold the engine (which needed the above main bearing work) to a guy in Newcastle who is a die hard LTR fan. He told me that he only rides it at Stockton and reckons it the fastest thing there, not that I cared to much.

Yup. Sounds like another one of those bikes that will be put together for under 800 bucks......

[firko]

. It's obvious now that the LT engine is crap. I didn't just take Bahnsys word, I googled the 'net and then rang Mike my friend in the USA who backed everything Rod said plus lots more. He's got "6 or 7" engines with spun mains and/or thrown rods gathering dust under his house. He told me that he eventually fitted a KX500 engine to one of his Quadzillas and he reports that it positively ripped! He said it was the quickest thing he'd ridden until he got his current Polaris. I didn't ask when talking to Mike (I should have) but I wonder if the the porting of the LT is in the same ballpark as the RM500 and whether the watercooled cylinder would fit the RM500 or even an earlier RM400 bottom end and if they do, is there a good readon for doing it?

I've been talked out of the LT/RM so it looks like a 465 Yamaha will probably get the treatment unless I can find a good early ATK 406 or even a 4T 560. I've got an '81 XL500 and have access to a Magnum Maico frame but as trick as they look,  I don't like those kind of conversions much. You can spend your whole super on the Honda stroker and still be off the pace to a stock CR/KX/YZ/Maico/Husky 2 stroke 500. An IT 465H I know of may just be a good starter. Are they close enough to the YZ to make it a worthwhile project base?

[Lozza]

Why didn't anyone think to put an anti-rotation pin in the bearing?

[firko]

I can't speak for others Loz but my mate Mike did pin the bearing plus going to a lot of trouble welding a heavier billet boss to the cases. That mod worked best of all but that kind of work is expensive and out of the reach of the average bloke. Apparently the contributing factor to the bearing failure is the inadequate web casting strength around the main bearing area which causes the cases to flex or distort under load, the results being the bearings eventually spinning in the case and ..disaster. Pinning the bearing or even the steel sleeve does prevent the bearing from moving to a degree but the weakness in the cases are still there causing the load to be transferred to the next weakest area with resulting cases distorting and eventual bottom end siezure. Mike was sponsored by Suzuki USA through a big California Suzuki dealer network back in the early 80's so you can bet they had their top guys on the job trying to solve the problem. As Mike said, the only cure they found was welding a whole new heavy duty main bearing boss and fitting wider main bearings. He told me there were an unbelievable number of hours just welding and machining the one set of cases they did. He won the big Mammoth Mountain GP quad event with that engine in '83 or '84 and then promptly retired the bike and went back to desert buggy and snowmobile racing. He reckons the Quadzilla was a good thing while they held together and if you kept the revs low and used the torque by riding in a higher gear than you would normally. He said that no matter what you did, the quad would eventually blow up, no matter how well maintained it wass or how carefully it was ridden. He reckons Suzuki had big plans for the engine but after they started shitting thremselves they quickly fell out of love with the model and quietly retired from both the 500 MX and Quad classes. Mike now rides vet class on a Polaris and occasional VMX on his KX500 and Rokon 340. He reckons he'd love to take his Quadzilla for a blat but is scared it'd blow up so it's now a garage queen.

[Rossvickicampbell]

just to back up an earlier coment re spares - when restoing my 250 the guy from Suzuki said I was lucky I didn't have a 500 as any and all spares were as rare as hen's teeth!

Rossco

[suzuki43]

Rossco they are still out there,if anyone needs some goodies send me a PM. I have some odds and sods i.e the rare as hens teeth inside and outside  chain guide plates for the 500E/F plus more....

[zorroz]

Check this RM500 engine - center port exhaust thats something I've never seen.



http://forums.mxtrax.co.uk/showthread.php?t=257162&page=5

[JohnnyO]

Could it be out of a quad bike.. were they aircooled?