Author Topic: Bike won't rev past 9k rpm (Read 5276 times)

JackBlack · « **on:** June 17, 2006, 06:52:07 PM »

Having some problems. It just won't rev past 9,000rpm reguardless of what gear I'm in. I've taken it on a dyno and from that it gets to 10,000rpm which is about 47bhp and then the fueling goes nuts and it just won't go past it. My fuel tap is completely fooked i.e. I just rode 80 miles with it on off hehe. I took the tank off a few weeks ago and it just pissed fuel out while in the off position. Do you think that changing the tap could sort the problem out or is there something else I should check out?
Jack

interfuse · « **Reply #1 on:** June 17, 2006, 08:30:22 PM »

Quote

My fuel tap is completely fooked i.e. I just rode 80 miles with it on off hehe. I took the tank off a few weeks ago and it just pissed fuel out while in the off position.
Jack

Off position? The normal fuel tap doesn't have an "off". It has on, res, and prime. On and off are the same setting, with and without vacuum. Here's a link to a diagram.

http://forums.banditalley.net/viewtopic.php?t=4216

The setting that isn't market is prime, if you have your bike set to that go turn it back to "on" and check your oil to make sure gas hasn't made its way into your crankcase.

JackBlack · « **Reply #2 on:** June 17, 2006, 08:50:54 PM »

It's a GK75A, one of the double disc imports. The fueltap doesn't have anything written on it but this is a pic of what it looks like.
http://www.banditspares.com/images/items/itm_2068_11195558781_m.jpg
I know the GSXR 400's have a prime on the tap but I was pretty sure these didn't

JackBlack · « **Reply #3 on:** June 17, 2006, 09:10:50 PM »

ok well just been reading up, the tap in mine turns 180o from top to bottom. Which position is On and what's Reserve? If my taps busted and fuels just comming out anyway do you think replacing it will fix the fueling problem??

interfuse · « **Reply #4 on:** June 17, 2006, 11:12:02 PM »

Looks like the standard fuel tap to me. On/off is bottom postion, reserve is the next position up (shown in the pic) and prime is the top position. If you disconnect the tank with the fuel tap on "on" and fuel comes pouring out then your tap is dinked. If its dinked, fixing it is the only option. Either replace the mikuni petcock (read $$$), or install an inline shutoff.

I doubt the fuel tap is the cause of the rev'ing problem. Personally I'd start with cleaning the air filter & changing the plugs. Then get into the more serious stuff like carb tuning & valve adjustment.

JackBlack · « **Reply #5 on:** June 19, 2006, 01:19:49 PM »

Ok i've just read one of Jay's REALLY old posts and he says about a CDI restrictor. If there's 7 wires comming out of it then it's got a restriction there, had a look and what did I find.. 7 wires :-D just curious if it would restrict the revs to 9k or just the top speed

JackBlack · « **Reply #6 on:** June 19, 2006, 01:26:13 PM »

http://forums.banditalley.net/viewtopic.php?t=530 that's the post

wyntrblue · « **Reply #7 on:** August 10, 2006, 06:30:35 PM »

sorry to res an old post...

i was riding home today, doing about 70mph bikes behaving fine, reving normaly....

then suddenly the bike loses power, and wont rev over 8k in any gear, the note of the engine changed as well, and the bike was louder, alot louder.

first thought was that the end can got blown off again (same thing happened a few weeks ago and it was the end can, but that was attached fine.

anything you guys can suggest to a cause would be great, i will be checking air filter and plugs in the morning when its light, but as my bandit is my only transport i really need to get this sorted asafp......

gsxr400 racer · « **Reply #8 on:** August 10, 2006, 10:29:34 PM »

Quote from: JackBlack

Ok i've just read one of Jay's REALLY old posts and he says about a CDI restrictor. If there's 7 wires comming out of it then it's got a restriction there, had a look and what did I find.. 7 wires :-D just curious if it would restrict the revs to 9k or just the top speed

just speed!!!

wyntrblue · « **Reply #9 on:** August 11, 2006, 05:39:01 AM »

got a question in relation to this thread...

if the oil is really really low in the bike would that stop the variable valve timing from changing the cam profiles? my thinking is that if the electric single is sent to advance the ignition but there isnt enough oil for the pressure change that changes the cam profiles it would then struggle to make any power and wouldnt be able to rev to high...

i could be totaly wrong but what are your thoguths?

gsxr400 racer · « **Reply #10 on:** August 11, 2006, 08:04:17 AM »

I dont have any experience with the VV other than the piston sizes, Is that how it works on oil pressure? Interesting!

wyntrblue · « **Reply #11 on:** August 11, 2006, 08:18:15 AM »

my understanding of it (and i admit that is somewhat limited) is when the bike hits 8k revs a sensor sends a signal to a valve thingy and it reverses the flow of oil to the top of the engine and the flow changes the lobes of the cams and changes the profile. the sensor tells the cdi to change the ignition timeings so i think the problem is, the sensor tells the cdi to change the ignition timing and redirect the oil flow, the oil flow isnt changing the cam profile, that means that the sparkplugs are firing at the wrong time and thats whats causing it to not rev properly......

again this is my understanding, but as i said my understanding is somewhat limited