Yamaha TRX850 Enthusiasts Forum

Yeah, ‘whoops’ is an understatement. I've been adjusting my valve clearances. I was having a bit of trouble getting the markers on the cams to line up ok, but in the end I got them spot on. The oversight was in all the fiddling about I’d forgotten to torque up the exhaust cam sprocket bolts properly. So, fast forward to me riding around feeling pretty good about the work I’d done - then ping, silence - something terrible has happened. I pushed the bike back home and took the cam cover off to have look. Inside is a broken cam chain, then I notice a lack of bolts on the exhaust cam sprockets - i'm feeling a little ill by this point. I then take the oil pump cover off and see the bolts very chewed sitting next to a toothless crank gear.

I didn't mean to ruin it, but couldn’t have do a better job if I tried! I guess my valves are shagged too. Can you get a new gear put on the crank? It's also taken a chunk off the inside of the engine casing (see the pics) is that something that can be filed away nice and neat or was it necessary?

So what are my options? I'm looking at new valves, crank and crank case. Would the mk2TDM 850 parts be interchangeable to repair this horrible mistake? All this means a total engine re build, anything else I should do while it all in bits? What special tools will I need to undertake the job?

Here are the gory pictures -

666mph wrote:Yeah, ‘whoops’ is an understatement. I've been adjusting my valve clearances. I was having a bit of trouble getting the markers on the cams to line up ok, but in the end I got them spot on. The oversight was in all the fiddling about I’d forgotten to torque up the exhaust cam sprocket bolts properly. So, fast forward to me riding around feeling pretty good about the work I’d done - then ping, silence - something terrible has happened. I pushed the bike back home and took the cam cover off to have look. Inside is a broken cam chain, then I notice a lack of bolts on the exhaust cam sprockets - i'm feeling a little ill by this point. I then take the oil pump cover off and see the bolts very chewed sitting next to a toothless crank gear.

I didn't mean to ruin it, but couldn’t have do a better job if I tried! I guess my valves are shagged too. Can you get a new gear put on the crank? It's also taken a chunk off the inside of the engine casing (see the pics) is that something that can be filed away nice and neat or was it necessary?

So what are my options? I'm looking at new valves, crank and crank case. Would the mk2TDM 850 parts be interchangeable to repair this horrible mistake? All this means a total engine re build, anything else I should do while it all in bits? What special tools will I need to undertake the job?

Here are the gory pictures -

OMG....R.I.P
http://cgi.ebay.de/Yamaha-TRX-850-4-UN- ... 5886a453ce

Cheaper than a new crank....

The second one has to be worth a bid, and it just needs to be fitted. German one is way too expensive, and you have to get it to the uk as well.

Dave E

Yeah. I was thinking it might be cheaper to just get another engine. This one from the TDM

http://cgi.ebay.co.uk/Yamaha-TDM850-3VD ... 4a9f96ce70

It's the 360 degree crank type but with some TRX bits in there? If I get a TDM motor (the Mk2 270 degree one) how much of it will i need to swap into my trx to keep my bike all trx - if you get what i mean.

I guess i'm going to have to put the TRX in the corner and wait on ebay for a parts bike.

What a bummer!

Cheapest options gotta be a "new" TRX engine I'd say. They can be had for £300-ish but dont turn up that often.

Otherwise, if you can nab a whole bike for £1,000-ish, you can use the motor and ebay the other bits and probably make most of your money back! ...if you can be bothered with all the ball-ache of it.

Or break up and ebay whats left of your bike and buy another!

Ouch! My worst nightmare.
Please note there's a guy advertising with crankcases here in the NL, it is without crank though.

Sorry to see that, what a @#$!ing shame!
I actually winced in pain when I saw your gear...
Good luck finding parts mate.

My deepest condoleances...

But hey, it might be your lucky day:
http://trx850.motomaniac.net/forum/view ... =33&t=5261

you have pm

You can have crank 4 free 666. May be able to get you complete head also. As a favour

Killerwhale wrote:

666mph wrote:Yeah, ‘whoops’ is an understatement. I've been adjusting my valve clearances. I was having a bit of trouble getting the markers on the cams to line up ok, but in the end I got them spot on. The oversight was in all the fiddling about I’d forgotten to torque up the exhaust cam sprocket bolts properly. So, fast forward to me riding around feeling pretty good about the work I’d done - then ping, silence - something terrible has happened. I pushed the bike back home and took the cam cover off to have look. Inside is a broken cam chain, then I notice a lack of bolts on the exhaust cam sprockets - i'm feeling a little ill by this point. I then take the oil pump cover off and see the bolts very chewed sitting next to a toothless crank gear.

I didn't mean to ruin it, but couldn’t have do a better job if I tried! I guess my valves are shagged too. Can you get a new gear put on the crank? It's also taken a chunk off the inside of the engine casing (see the pics) is that something that can be filed away nice and neat or was it necessary?

So what are my options? I'm looking at new valves, crank and crank case. Would the mk2TDM 850 parts be interchangeable to repair this horrible mistake? All this means a total engine re build, anything else I should do while it all in bits? What special tools will I need to undertake the job?

Here are the gory pictures -

OMG....R.I.P
http://cgi.ebay.de/Yamaha-TRX-850-4-UN- ... 5886a453ce

Cheaper than a new crank....

Just saw a new listing...
http://cgi.ebay.co.uk/Yamaha-TRX850-98- ... 51919c6ba8