Engine stops pulling at 7k

[hikermikem]

Instead of continuing to bug Steve and Ed on this problem I thought I would throw it out to the masses and see if any have experienced something similar.

Been working on a 1980 750E with 5900 miles on it. The problem I am having is during exceloration at about 7000 rpms in any gear it stops pulling or feels the same as hitting a rev limiter on a modern day bike. Under 7k it runs like a champ, smootha s silk...

Here is the skinny..

5900 miles
Stock exhaust
Carbs cleaned and rebuilt with new stock mains and pilots
Stock airbox and new filter
New Battery
New plugs
New Petcock
POR 15 tank liner ( no rust, tank is clean )

Didn't see a valve adjustment on your list? New plug caps are always a good upgrade.

This old post of mine is about my VERY hard starting 750: http://www.thegsresources.com/_forum...d.php?t=143270

[hikermikem]

If you open the carbs again you might as well raise the needles too...

[jwhelan65]

No valve adjustment done, it runs fantastic until you hit 7k..I may adjust the floats and see what happens???

[jwhelan65]

I swapped ignitors from my '82 1100 to 750 no problem. Is the '80 750 a different plug setup?
I have both timing plate and ignitor here collecting dust if you need them.

Connectors are different on the 80

[hikermikem]

No valve adjustment done, it runs fantastic until you hit 7k..I may adjust the floats and see what happens???

If the bike truly has only 5900 mi on it, I would wonder if the valves have EVER been adjusted... quite possibly the entire reason it starts so hard.

[jwhelan65]

If the bike truly has only 5900 mi on it, I would wonder if the valves have EVER been adjusted... quite possibly the entire reason it starts so hard.

I doubt they were, it had been sitting since 1982 in a controlled climate storage unit.

[hikermikem]

I doubt they were, it had been sitting since 1982 in a controlled climate storage unit.

She's a beauty Joe !! Ya gotta adjust those valves first though, should make quite a difference.

[El Giablo]

It is definitely not an intake/vacuum leak. It is either starving or retarded G.

[waterman]

How is your air filter, lightly oiled? My brother's air filter was dripping with oil which helped compensate for the half teaspoon of fine rust I pulled out of his carbs. He bought it new in 80, had about 60K miles on bike, never had carbs off.

Nice looking bike. Would be proud to own such a beauty.

[jwhelan65]

It is definitely not an intake/vacuum leak. It is either starving or retarded G.

Sounds like valves and float level for starters

[jwhelan65]

How is your air filter, lightly oiled? My brother's air filter was dripping with oil which helped compensate for the half teaspoon of fine rust I pulled out of his carbs. He bought it new in 80, had about 60K miles on bike, never had carbs off.

Nice looking bike. Would be proud to own such a beauty.

Thanks

It is a dry stock OEM replacement filter..

[El Giablo]

Beautiful bike. I would start with the carbs. Valves do not get tight from sitting... G.

[mlinder]

ver ver pretty bike.

I'm mostly with Pos...popst.. whatever, the guy from Santa Barbara. I think it's ignition. Either low voltage or broken advance/timing.


/edit: posplayr

[hikermikem]

Beautiful bike. I would start with the carbs. Valves do not get tight from sitting... G.

Agreed, but they are tight because they've most likely never been checked/adjusted since new.

Suzuki service manual states to check/adjust them at 600 mi, 4000 mi and again at 7000 mi. This bike is approaching 6000 mi & it's unknown if the valve cover has ever been off.

My guess is they are long overdue for an adjustment. Not saying this is the ultimate fix, but the hard starting is a classic symptom of tight valves.

Could also contribute to why it's not revving completely either - the valves can't open enough to allow enough fuel mixture into the cylinders.

[Mysuzyq]

+1, on the valve check/adjust to begin with...might as well, if it's unknown whether the P.O. did do it. Take a look at venting too (via the fuel cap)...next time it dies whilst riding, open the cap, watching (listening) for a vacuum of sorts, and see if it starts with the cap partially open.