Dying due to air promblem or overheating maybe?

[Viirin]

I been having some issues with my GZ as of late - if i have a clear run for about 90 seconds at about 35-40 mph, the bike looses power and then the engine cuts out all together. The bike can't be started immediately but it can be after about 40 seconds but then the idle sounds very uneven and if it's ridden again, dies in about 100 meters. sometimes if i've got a fairly long run up to a set of lights i can hear the engine idling at about half of what it normally does and then it feels like a race to for the lights to turn so i can get going before it cuts out. - I thought the bike wasn't getting enough fuel but i checked the line and it seems fine. Maybe it isn't getting enough air or is overheating or both. I guess it could always be the carb again but the overheating idea just came to me because i had such a nightmare with it last summer and it always seems to break down on the sunny days Any similar experiences you guy could share would be greatly appreciated as it might save me pushing it 4 miles down the motorway/free-way to the next exit in full gear! thanks.



just before i forget so far i've :
checked/cleaned the fuel line - seems clear
checked the oil level - seems fine
added some fuel additive just in case

thanks again
Vii

[JWR]

Does it do this with the fuel lever in the PRI position??

[BillInGA]

Originally Posted by JWR

Does it do this with the fuel lever in the PRI position??

That's a great question. My initial thought was fuel starvation, although you said you checked the flow from the tank.

You may have a vacuum leak between the carb and the fuel valve, causing the fuel valve to shut off fuel when it's set to ON or RES.

[blaine]

Let the carb cleaner work for a while to see if there is any difference in the way it runs then you will know if you have a carb problem or not.It sounds like your carb is plugged and when you let bike sit carb fills up again.

[Viirin]

I'll stick it on Prime tomorrow and see if it's a vacuum problem but there seemed to be decent suction from it last time I had the tank off which wasn't too long ago - is it common enough for them to get blocked or loose suction?

How often should you clean or replace the air filter? Could a dirty one stop the air from cooling the bike or even starve the combustion chamber?

[JWR]

I don't think the filter is your problem.

Will the bike rev up in neutral when you first start it up??

[blaine]

Not common to lose vacuum unless diaphain is gone in petcock.Fuel would still flow if in prime possision.Filter should be changed if dirty on the INSIDE or oil soaked.If engine running very lean will cause it to overheat.Plugged filter will cause engine to run very rich and flood.

[Viirin]

Yeah she'll rev fine in neutral, it only dies after a long stretch of consistently high revs but after that it has trouble even in neutral...at least for about 30 minuets. It's so strange, it's like it has more trouble idling after it gets warm which is completely counter-intuitive to what i normally think. I had it running today for about 10 minuets in neutral and it didn't seem to have an problems ticking over at the normal pace (but i never thought of setting it to PRI).

Thanks again for getting back to me so quickly - I got exams coming up in the next couple of weeks and i'd be sunk if i couldn't get the bike running - you guys are life savers!

[Viirin]

oh no - just checked the fuel line and it's keeps flowing even when it's in the PRI position - what kind of implications does this have? not good i'm guessing...

[BillInGA]

The fuel is supposed to keep flowing when the fuel valve is in the PRI (prime) position. The question is whether the engine continues to act up when you ride with the fuel valve in PRI.