Topped out my 82 750E (and found some new fun problems!)

[gliscameria]

I just had some repairs done to my bike before heading from Phoenix down to Tuscon, so naturally I totally abused it on I10.

I don't know if it was favorable winds or the aftermarket carbs/exhaust and wierd crud the guy before me did to it, but I got to 9K in 5th gear.

If my sproket is stock size, I think that's up around 120-130?

However on the way home I discovered I'd been leaking gas down into the engine (stupid petcock) for quite some time and sprung some very entertaining leaks... along with having entirely too much 'oil', I'm hoping this is the cause for the profuse leakage around the breather. It's only leaking while it's running, so I'm hoping it's just some old ratty gaskets combined with super thin 'oil', (more the consistency of diesel fuel at this point).

Time to order a new petcock! =)

 

[ccratin]

Sorry dude. Yep, it's probably coming out the crankcase vent. Drain that stuff and put in fresh oil. Make sure that it is really the petcock leaking though because usually if it's filling the crankcase you have some float needles not stopping properly and potentially have a petcock problem too. does yours have a PRI (prime) position? IF so, is it left on that?

 

[gliscameria]

Cool.

It's got three positions, reserve, run and prime. (I think thats it)
Reserve at 9, run at 6 and prime at 3

I leave it at 6. If it's left at 3... well, it drains the tank. =)

I'm waiting to see what my mechanic says, because I'm beginning not to trust him. It looks like the oil is mostly leaking from the very front of the engine near the center, I was told thats the breather?

 

[ricardo]

dont ride under these conditions, i did and when the gas/oil mix finally hits the back tire things get really exciting. this is something you want to fix now.

 

[gliscameria]

Fixed?

Fixed?

Well, had it in the shop for a bit...

He said he found a good pit of rust in the carbs and through the engine, so he cleaned out the carbs, adjusted the valves and replaced the valve cover casket and breather gasket... No more leaks (other than the half moon cam cover thing blowing off... =), which is fixed)

I'm still having issues with performance though. He installed an inline fuel filter, which already seems to be catching some crud. I can run it just fine, and pretty hard, on surface streets, but if I have to maintain 65mph or so in 5th gear I loose all power, I can coast on the burm for a few seconds and get back up to speed though.

The petcock was rebuilt when i had it first serviced, however I'm thinking that maybe the source of the rust was in the tank, and perhaps I got some crud in the diaphram since then.

Does it make sense that I would lose fuel flow at medium throttle and low RPM but not at high RPM if there was a fuel flow issue? (IE - riding on the highway in fifth gear loses power, but hauling ass through traffic in 3-4th never causes a problem)

Also, if I really rev it, I get a huge boost in power when I hit about 7-8K. I mean it sounds like a whole different engine and it really moves.

I'm debating taking the petcock apart, any ideas?

//Glis

 

[Roger P.]

My 83 550E used to do the same thing when run flat out for a long time. I think the lack of engine vacuum at wide open throttle causes the petcock to shut. You could put it in prime and try again. It was an intermittent problem, sometimes it would happen, sometimes not.