Trouble at 8,000 RPM

[leesh00]

I took the bike out for a run yesterday and found that when I got to 8,ooo rpm the power kept dropping off, I played with the throttle and it did get passed it but didnt feel quite right even then.

It was yesterday so probably the highest temps ive had it out in - dont know if this might have effected it? I had it serviced a couple of months ago spark plugs changed and k & n cleaned.

Any ideas and tips where to start please :)

[Alpinestarhero]

Which model year is your SV to start with :D

[vardypeeps]

Is it restricted also?

[johnnyrod]

The foam hasn't fallen off the underside of the tank has it?

[Viney]

Dont go above 7900rpm then

HTH ;)

[leesh00]

Which model year is your SV to start with :D

Its a 99 and not restricted :)

[sunshine]

dont roll off the throttle and you wont lose power :thumright:

[xXBADGERXx]

I something loose under the tank like a heatshield or something ? Sometimes these can flap about and block an air filter giving you symptoms similar to this .

[johnnyrod]

My suggestion also. Same syptom but lower downt he rev range, 6k or so I think. Seemed very repeatable which confused the crap outta me for a while.

[boo86]

run some red ex through it. Unless you're confident with a carb strip down. At 10 years old I imagine some **** has built up in the carbs. It's either starved of air or fuel. Doesn't sound like an electrical prob. Check the in tank fuel filter too. I've had huge clumps of rust stuck in mine before on other bikes. I'd put money on it being a petrol delivery prob some-where in the fuel sysytem be it tank or carb.

[leesh00]

So ive finally had chance to have a look at the bike today heres what ive done so far - taken the tank of and checked the hoses and fuel tap, this all seems to be fine - i am presuming that the strainer filter which is part of the tap is what was referred to earlier as the in tank filter - any way this was clean and had no holes in it. The foam hasnt come of the underside of the tank and there isnt anything obstructing air flow into the filter or the carbs, however there was some fuel in the bottom of the air filter housing - is this normal? I dont know if i fancy attempting a full carb re build myself but before this happened i did run some redex through the system anyway. I will mention that on the day this happened i had a pillion on the back for the first time - the problem started straight after, dont know if thats relevant or not.

Any more diy ideas or is it off to the garage for the carbs sorting?? :)

[johnnyrod]

Fuel in airbox normal, I reckon you might have a blocked main jet - have you tried pulling the choke when it dies off? Cleaning out isn't so tough, and don't be sucked in by this overpriced ultrasonic gig which seems to be the latest moneyspinner, you don't need it in this case. Carbs of, clean out, blast all holes with WD40 (on the carb that is). Try the choke test first.

[yorkie_chris]

Yes something on the main jet circuit, is it under wide open throttle condition?
If it is OK, then dies after a number of seconds under load, then it could be fuel starvation.

[leesh00]

Yes something on the main jet circuit, is it under wide open throttle condition?
If it is OK, then dies after a number of seconds under load, then it could be fuel starvation.

Weather permiting after work I shall see if it is under full throttle I get the problem I think it is, though now youve said it Im thinking is it?

Fuel in airbox normal, I reckon you might have a blocked main jet - have you tried pulling the choke when it dies off? Cleaning out isn't so tough, and don't be sucked in by this overpriced ultrasonic gig which seems to be the latest moneyspinner, you don't need it in this case. Carbs of, clean out, blast all holes with WD40 (on the carb that is). Try the choke test first.

This too.

[leesh00]

right ive got the carb off and have cleaned the main jet - pilot jet and needle jet (is the jets that the needle jet sits around removable - it doesent look like it is so ive sprayed it with carb cleaner in place) apart from these is there anything else in the carb that i should do that might be causing this problem :)

[leesh00]

by the way all the jets that ive looked at have been clear (to the eye) you can see straight through them with no apparent build up.

I did try the bike this morning before i did this and it is only with 3/4 to full throttle it happens. Tried the choke when it did it and this made no differance.