rod play? how much is ok?

[Sickboy]

Hi I have a 2001 CR250, and I've torn it down to where the engine is out of the bike and I'm going to try replacing the crank seals. The bike was running great when I took it apart aside from seriously smoking like crazy all the time, and losing oil from the transmission. Top end looked fine, a little wear but I could see the hone marks everywhere on the cylinder yet. No problems with the bottom end except a suspect crank seal. My question is if my rod bearing is ok... I have a little side to side movement, but pretty small... I don't have the specs yet but I will get a feeler gauge and measure it. There is no up and down play at all, however, when gripping the top of the rod and moving it side to side there is significant play, in other words it can rock side to side on the crank. Is this a big deal ? What type of bearing is the rod bearing?

 

[2strokerfun]

Some sideplay is normal. You'll have to look in your manual to see how much is acceptable for your paticular model of CR. If you don't have a manual--even a Clymers or Haynes--then get one. Hope you're up and running soon. Spring slowly approaches......

 

[dirt bike dave]

Some side to side movement is normal, but it should not twist or have up and down movement. The original Honda shop manual is very good and worth the money if you plan to keep the bike. One thing the shop manual will tell you is the crankshaft assembly is a maintenance item that should be replaced every so often (can't remember the hour interval).

FWIW, complete CR250 crank assemblies (crank, rod, big end bearing) are not very expensive. I think I paid $160 for a brand new Honda OEM assembly for my '99 a few years ago from Mach 1 Motorsports. Service Honda can also get you a good price. On a CR250, by the time you buy just the big end bearing, find someone to split the crank and re-assemble, ship the crank, etc... you might as well just get the peace of mind and convenience of ordering a new Honda crank assembly, IMO.

When I did mine, new right and left side crank bearings were also not too bad ($30+- each side). The complete gasket kit is maybe $70+-.

The reason I had to repair mine was the big end bearing let go and trashed the right side of the crankcase (another $160). Had to put in a new piston kit, too. Luckily, the cylinder, head and powervalve assemblies were not damaged by all the big end bearing bits.

 

[Sickboy]

I checked the side to side clearance with a feeler gauge and it's well within specs... according to the Clymer manual I got. There's no crankshaft play at all, so I guess I'm just going to replace the crank seals and button it back up, with the new top end of course. The clutch looked great and the plates are withing spec. I do notice however that I have a hairline crack in the clutch side case cover. Does anyone sell these?
Maybe next time I need a new top end I'll either put in a new crank/rod assembly and bearings, or just send it to Eric Gorr and have the whole thing gone over. Thanks for the help