rvf400/nc35 power problems(electrical issue?)

[Neosophist]

Balancing the carbs will not change peak power.

All it does is synchronise the vaccum at IDLE.

This will give you a smooth idle as all 4 cylinders are being fed the same amount of fuel/air mix.

When you are on full throttle the butterflies are open fully and the needles raised to their maximum.

I've read through the thread and you state a few times that you trust these guys to sort your bike out but you are asking people on here for advice? Maybe you don't trust them enough to fix your problems..

Compression test: What were the results for each cylinder, have you seen them compression test it? Do you have the results for each cylinder?

Chopping and changing random parts without knowing why won't usually solve the problem unless you try enough things to stumble upon the solution.

Kev over at Projex engineering is a dyno operator and owns an RVF400, stock dyno run was 49bhp but with a free flowing system and appropriate carb setup he's got the bike upto 64hp.

I don't believe that the Tyga system is your problem.

You need good compression (test this and post results, along with numbers for valve clearances)

Appropriate fuel / air mix - This relies on carb airbox / rubber flaps being inplace, correct jets and needles as well as clean air filter and good fuel flow.

Ignition: Your plugs need to work and not break down, as well as the coils and leads being in good condition.

Ancilliary drag such as worn sprockets and drive-chain, wheel bearings and rear-brake can all zap power from the motor too, check over these.

As Mark has said numerous times, there isn't a great deal of things that can restrict your power. With a free flowing system and approrpriately setup carbs and a healthy motor, circa 60bhp shouldn't be unreasonble to expect from a stock engine.

If I were certain that the carbs were setup properly (airbox and flap inplace) and the system had no leaks, the first checks i'd perform would be compression and ancilliary drag.

Electrical issues can cause problems too and it'd be wise to ensure you have a good battery and have tested the charging system.

Even something stupid like an airleak on the carbs or the balancing screws leaking air will alter your bhp.

Hopefully you can isolate the problem and fix it.

[peavey]

No your right I dont trust the shop after balancing the carbs myself. Ive never said that the tyga system was a problem either I am just after an original set up
I am just setting the bike up as standard and goin from there, I'm learning as I go along and not spending a fortune doing it this way.
I will do a compression test and valve clearances and post results
what is the flap you are talking about at the airbox? and whats the best way to test for an airleat at the carbs?

[Neosophist]

Well if you already have the Tyga system it's goign to make more power with it than the stock system.

Since this shouldn't be an issue it's probably easiest to tune the bike to this exhaust from the get-go.

Air-leak will present itself by the revs hanging, usually around the 2000rpm mark for a second or so before they return to idle.

The rubber flap goes infront of the airbox, without it you get odd runnign issues at full throttle when theres a lot of airflow.

Get the compression test and valve clearnaces checked first, this will prove that the motor is a good runner.

Once this is done can go from there in getting it working better, but until you have solid numbers regarding compression and clearances, trying anythign else is meaningless. It'll get there :)

[peavey]

So is that flap on the airbox itself or is it the rubber matt thats attached to the frame in front of the airbox ?

[skinnydog0_0]

Yer it's the rubber flap that attaches to the frame and fits over the inlet ports.

[peavey]

Ive just got to doing the valve clearances this week and the results are shown in the pics below ( if someone could put them please as it just says( It was not possible to determine the dimensions of the image.)
these are the links
http://s1096.photobucket.com/albums/g33 ... nt=519.jpg
http://s1096.photobucket.com/albums/g33 ... nt=524.jpg

They aint good and ive done the sums on shim sizes .
I need :
2.23
2.18
2.28
2.08
2.10
2.23
2.12
some of the shims being replaced will be used again, where is the best place to get the shims above?

[peavey]

Ive got the valve clearances done and have just done a compression test on each cyclinder with the carbs off and the engine cold the results were
cyc1-100psi
cyc2-110psi
cyc3-100psi
cyc4-110psi
I will do these again on a warm engine and see what the results are but I just tought I woukd show results from a cold engine first
what do yis think?

[CMSMJ1]

The valve clearances aren't "bad" they are only a touch here and there out of spec. Nothing that is indicating major issues.

Compression seems low though...which is not good.

[peavey]

yeah they were all in tolerance except 2 but I set them all to midrange tolerance seeing I was at it .

the compression results are scary and im going to warm the engine up ,do it again and see what the results are

[peavey]

Ive just completed the compression test on each cyclinder after warming up the engine and the results did not change and after a few squirts of oil and a recheck the compression rose on each cyclinder to 150psi
what do yis think of that ?