Non GS, plain bearing crank advise

[rphillips]

A friends brother-in-law's "86" Kaw Concourse. Sat 3 months, charged batt. fired right up. Idled fine appx. 2 min, then gradually siezed up & quit, while still idleing. Found crankcase full of gas & oil mixture. What to expect, worst to best. Kind of scared of the plain bearing crank.

[Mark M]

A friends brother-in-law's "86" Kaw Concourse. Sat 3 months, charged batt. fired right up. Idled fine appx. 2 min, then gradually siezed up & quit, while still idleing. Found crankcase full of gas & oil mixture. What to expect, worst to best. Kind of scared of the plain bearing crank.

Well, it was at idle, which is very good because loads are low and it will stall out easily, minimizing any damage. At a minimum, you will be rolling in new bearing shells (both crank and rod). Probably will need to have the crank polished because it will have picked up a lot of bearing material as it siezed. Worst case will be replacement of the crank and some rods if the bearings spun and screwed up the fits. I doubt that would have happened at idle, though. It usually takes some harder running for a while to cause the shells to spin and heat up the rods or main saddles.

Mark

[tconroy]

A friends brother-in-law's "86" Kaw Concourse. Sat 3 months, charged batt. fired right up. Idled fine appx. 2 min, then gradually siezed up & quit, while still idleing. Found crankcase full of gas & oil mixture. What to expect, worst to best. Kind of scared of the plain bearing crank.

Are you sure it's seized? Drain the oil and pull the plugs and put some mystery oil in the cylinders for an hour or so.Then put it in gear and try to move the back wheel. If you lucky it could be a ring that stuck or maybe something not so severe.

[Dave8338]

Add to that list...cam bushings. They are farthest away from the pump.

[tconroy]

Add to that list...cam bushings. They are farthest away from the pump.

Thats kinda what scares me about our bikes Dave.The 83 650 shafties also have engine sleeve bearing like a car and we also have a high pressure oil system unlike the roller bearings and low oil pressure system the chain drive models have.Why didn't they just stick with the roller bearings?!!

[Nessism]

Thats kinda what scares me about our bikes Dave.The 83 650 shafties also have engine sleeve bearing like a car and we also have a high pressure oil system unlike the roller bearings and low oil pressure system the chain drive models have.Why didn't they just stick with the roller bearings?!!

A better question is why did Suzuki bother with roller bearings in the crank in the first place? My guess is that it was a hold over from their two stroke days. Nothing wrong with them per say but they don't really do anything either.

Regarding the bike in question, best case is change the oil and fix the stuck float/petcock and the bike will be fine. Pull the plugs of course to make sure the engine did not hydro-lock. Worst case is hard to predict: seized, spun crank bearings, scuffed cams, etc. I think this is unlikely though.

Good luck.

[rphillips]

Thanks guys, kind of what I figured. Considering buying it, ???? Oil change, Mystery oil, & fix fuel problem, its a bargain, complete engine, not a bargain. To Nessism's question, My opinion, plain bearing cranks are much cheeeeper to manufacture than roller bearings. I'm still stuck on the roller bearings. Another odd observance, My Honda CB 1100 F, & my Kaw KZ1300, both have plain bearings & both I need to add oil between changes. None of my roller bearing bikes need oil between changes, & over the years, most roller bearing engines don't. Maybe to do with the difference in oil pressure?????

[Dan Ruddock]

Plain brg engines can be built to be lighter and more compact than a roller engine. The plain crank will never twist out of index and the service life if maintained properly is as long as a roller crank. Roller cranks are more sensitive to detonation damage and need a special tools and skills to rebuild. I have to agree with Nessism it was a hold over. It is not a cost decision but a it is a better way to do a four stroke decision. Dan

[RobGS850L]

The real deal with plain bearing cranks is cheaper, lighter and stronger. The lighter stronger part is what helps the engines power output. The cheaper is what helps us afford one.
Sorry Dan I was typing ever so slowly and didn't see your post yet.
So what Dan said too.

[Dan Ruddock]

Rob where is Isleton. Also a roller crank has less hydro dynamic friction but it is not worth all the other down sides. Dan

[focus frenzy]

Add to that list...cam bushings. They are farthest away from the pump.

what cam bushings?? the connie, like pretty much all aluminum head engines (gs included) run the cams dirrectly in the head, no bushings or bearings. the aluminum acts as the bushing, as long as it is getting oil it is perfectly fine.

it might have been the cams that siezed.

[Dave8338]

what cam bushings?? the connie, like pretty much all aluminum head engines (gs included) run the cams dirrectly in the head, no bushings or bearings. the aluminum acts as the bushing, as long as it is getting oil it is perfectly fine.

it might have been the cams that siezed.

Well, there you go...with a little luck, I'll never quit learning! :-D I guess that would explain why when things run dry, you'de be looking for another head.

[RobGS850L]

Rob where is Isleton. Also a roller crank has less hydro dynamic friction but it is not worth all the other down sides. Dan

Dan if you were to go up I-5 until you are 30 miles south of Sacramento and turned left onto Hwy12 west you'd then go 15 miles and we are to the right 2 miles from the highway. It's in what they call the Delta area. Isleton is right on the side of the Sacramento river. Here's a link http://www.isletoncoc.org/oldtown.htm
Back on topic sorta' I was also wondering if the Prostock bikes that were running GS style engines were still using roller cranks. If so that would mean they could (the bearings that is) run some pretty good rpm's.
And really on topic. Wouldn't the engine still having had fluids in it maybe the crank and such be ok since the oil pump was still more than likely working? Maybe my wishful thinking.

[Dan Ruddock]

Wouldn't the engine still having had fluids in it maybe the crank and such be ok since the oil pump was still more than likely working? Maybe my wishful thinking.

I would say it should survive, I have seen many engines live after a gas in oil problem. This engine needs to be diagnosed to determine the problem. I could see a failure if the engine was running at peak hp but not just idling. Dan

[t3rmin]

You sure it seized, or did it just die 'cause the floats were still overflowing and flooding the motor?