As I stated in my last post I just bought a 1982 RM250 to rebuild. It runs, It shifts, it doesn't make any abnormal noises. I have felt through the intake and at least so far the lower end bearings seem good. It does have low compression. If it passes a leak test and after I tear the top end down to rebuild it and if the lower end still feels good should I split the cases anyway or as my dad would say if ain't broke don't fix it.
To Split The Cases Or Not Split The Cases That's My Question
- Thread starter DCR
- Start date
It's a 30 year old MX bike, do you even have to ASK if splitting the cases is worth the effort? :coocoo:
I know your dad, not really, but? There are a lot that enjoy a catastrophic failure. They never raced, or relied on their bike? I never got that part, once I understood about the engine and racing MX. Did you ever check to see what parts are not available? Those 4 tranny bearings are a prime source of vibration. 79 I believe Suzuki started running thrust washers, check the clearance, and check the big rod end bearing with a good light and magnifier. My 77~78 rms, I can get all the parts, except the rod. My 83 CR, no more cranks. Unless you own a good machine shop? Vintage Bob
- Thread starter
- #4
Yeah I have checked before I bought the bike, and looks like the rod, rod bearings and crank bearings are available, but not the shifting forks.
I don't think there is anyway this bike was ridden regularly it's whole life. I think somebody back in the day bought it rode for a few years than it sat for years then the wife made him get rid off it then it's been passed from Young kid to young kid each scaring them self. I believe this was probably it's life because of it's overall condition. like all the little rubber pieces are still there, even the rubber flap that goes around Full Floater struts, and look like they are only a year old. The only thing that really shows any wear is the rear shock and suspension pivots. Even the forks look good, good original plating on the stanchions, anodizing looks good on the sliders, and only a slight weep-age from the seals. The counter shaft as no play at all neither does the shift shaft.
Hear is my thoughts. As far as the crank and rod goes the only ones I have seen fail, since 1974 have been on bikes with shot and dirty air filters with holes in them, so if the crank and rod bearings are tight and with no resistance or other problems I don't see a lot of reason take the crank apart. As far as the transmission I have never had to replace any part in a transmission over the years. The shifting forks are a wear item, but I can't get them new any way, and if I take it apart and find they are .005" out of spec I am not going leave the bike apart until I find a set. I don't believe I mentioned I drained the oil and it looks good. I checked it with a magnet and even though the oil looked a little old it was free of metal particles. The other thing to remember is the transmission because of primary gear reduction only spins around 1500 rpm max. I would think as long as the gearbox has oil in it that is reasonably clean I would think they would last a long time.
Mean while I will check the rod bearings about every month while I collect all of the parts available from Suzuki and ebay, so I will be ready when it needs it.
I am going to leak test the engine today, and then I will take the head and cylinder off, so I can check the crank and rod closer and find out the bore size. If the bore size on it's last oversize and is worn .025" over that the I will start worrying about the lower end a lot more.
Thanks for ever ones post so far I will post back tonight and post what I find.
I don't think there is anyway this bike was ridden regularly it's whole life. I think somebody back in the day bought it rode for a few years than it sat for years then the wife made him get rid off it then it's been passed from Young kid to young kid each scaring them self. I believe this was probably it's life because of it's overall condition. like all the little rubber pieces are still there, even the rubber flap that goes around Full Floater struts, and look like they are only a year old. The only thing that really shows any wear is the rear shock and suspension pivots. Even the forks look good, good original plating on the stanchions, anodizing looks good on the sliders, and only a slight weep-age from the seals. The counter shaft as no play at all neither does the shift shaft.
Hear is my thoughts. As far as the crank and rod goes the only ones I have seen fail, since 1974 have been on bikes with shot and dirty air filters with holes in them, so if the crank and rod bearings are tight and with no resistance or other problems I don't see a lot of reason take the crank apart. As far as the transmission I have never had to replace any part in a transmission over the years. The shifting forks are a wear item, but I can't get them new any way, and if I take it apart and find they are .005" out of spec I am not going leave the bike apart until I find a set. I don't believe I mentioned I drained the oil and it looks good. I checked it with a magnet and even though the oil looked a little old it was free of metal particles. The other thing to remember is the transmission because of primary gear reduction only spins around 1500 rpm max. I would think as long as the gearbox has oil in it that is reasonably clean I would think they would last a long time.
Mean while I will check the rod bearings about every month while I collect all of the parts available from Suzuki and ebay, so I will be ready when it needs it.
I am going to leak test the engine today, and then I will take the head and cylinder off, so I can check the crank and rod closer and find out the bore size. If the bore size on it's last oversize and is worn .025" over that the I will start worrying about the lower end a lot more.
Thanks for ever ones post so far I will post back tonight and post what I find.
2strokerfun
Member
- May 19, 2006
- 1,500
- 1
On a used two stroke, I always split the cases, replace just the main bearings and seals (and of course the gaskets). I feel the transmission bearings for problems and I measure the rod. Also put in new piston, rings, wrist pin and bearing so I have a baseline for the future. But I don't measure the transmission parts if they look fine and were shifting fine when I split the cases. Some day I'll probably wish I had.
I would dissassemble and replace all bearings and seals including the con rod big end bearing and thrust washers. and while in there inspecting all and seeing what is available and keeping an eye out on the auction sites for anything that you might be finding suspect while riding on used pieces with new bearings and preparing for the future.
- Thread starter
- #9
Well I am going to split the cases after all. It failed a leak test and the air was coming out the gearbox vent. After removing the primary cover the crank seal on that side has failed, but after closer inspection the rod still looks good, but I will be able to inspect it further once get the cases split this week end.
EncyclopediaRonnie
Member
- Nov 8, 2010
- 142
- 0
DCR said:
you sir are 1 lucky bloke
I don't want to poo poo your ecellent find( I love the 82 rm ) but it is possible that a a new cylinder was put on a trashed top end 15 years ago.........
"Well I am going to split the cases after all. It failed a leak test and the air was coming out the gearbox vent. After removing the primary cover the crank seal on that side has failed, but after closer inspection the rod still looks good, but I will be able to inspect it further once get the cases split this week end.
"
well I am glad you did a pressure test, would have seriously hated if it started up and took it for a full throttle blast and have a lean sieze... I think you are going to find out that you are lucky having to split the cases especially just for the piece of mind
"Well I am going to split the cases after all. It failed a leak test and the air was coming out the gearbox vent. After removing the primary cover the crank seal on that side has failed, but after closer inspection the rod still looks good, but I will be able to inspect it further once get the cases split this week end.
"
well I am glad you did a pressure test, would have seriously hated if it started up and took it for a full throttle blast and have a lean sieze... I think you are going to find out that you are lucky having to split the cases especially just for the piece of mind