VFR work Q&A

[killa]

So I need some work done on the VFR.

Just wondering if any of you have had a VFR in the past or maybe you’ve worked on one which needed some Heli-coils putting in, I am not sure how long it would take to replace the two rear threads, requiring taking the head off. I just wanted to know so I don’t get shafted on dodgy labour times.

Also, how would you check for an air leak?
I need to adjust my chain tonight, I haven’t got a paddock stand so is there anything I need to bare in mind when doing it in situ.

Ta

Killa
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[Jammy-R6]

You should take the head off yourself and take it down will hardly take any time to helicoil and will save you alot, remember to get them head gaskets ordered though.

Are you doing your chain with the C-spanner or drift and hammer? Spray some plus gas round the adjuster disk and remeber to put the correct torque on the pinch bolt when done. I think (looking at it from he chain side), anti-clockwise moves rear wheel out to tighten chain and clockwise moves the wheel in.

[killa]

Kool thanks a lot, yeah I forgot about the gaskets, will get them also.

I should be able to get the head off now problem, and the chain sounds simple enough.
I haven’t got a torque wrench though.
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[killa]

Ok an update on this work to be done……

I had about 3 quotes from various garages for the heli-coils, taking the head off, gaskets etc it seems the rough price is going to be around £250.
First off, does this sound about right to you?

Ok, so the problem I’m getting with the bike is poor throttle response at certain rev ranges, sometimes the bike seems to bog down/splutter before kicking in with full power.
The rear two plug threads are buggered from someone over tightening them, they were hand tight in the threads the last time the bike went into the garage so they put some lock tight on them for a temporary measure.
They are in there pretty tight now, I’m not moving them.

My question is, I’ve had the oil filter, oil changed, new air filter, shims replaced, new plugs, and basically a general look over…. Would you say the plugs are causing this problem?
A guy at work suggested an air leak, but I seriously don’t think that would be possible, I’ve had a look at the air box and filter and it is pretty much perfect condition, unless you can get an air leak else ware.
Any thoughts welcome, I need the plugs done anyway but it would be a shame if all this is done and the problem is still there, it is not a major mechanical problem but as I am no mechanic I really don’t know what else it could be.

Thanks

Killa
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[Davo]

I'd be more inclined to have a look at the carbs, my CB-1 was doing the same thing, just drained the bowls, made sure they were all joined up with the airbox and engine properley and re-balanced them.

It made such a difference.

I'm under the impression if it was the spark plugs causing the problem, it would have problems across the whole rev range.

[EuropeanNC30R...]

If they were going to loctite the plugs in you'd have thought they would at least used new plugs

You want to check for an air leak on the exhaust, especially under the engine where the two front header pipes meet the rear section. If it leaks there the fuelling will go fluffy, happened to mine.

[killa]

Thanks

TBH I did think if the plugs were being dodgy the bike would be fluffy all over the rev range, it is only on occasion, usually on heavy throttle use in the mid range say if I keep blipping it.
I was doing this on purpose at the weekend to see where and when it happened.
The pipes seem fine, no blowing, and no air leaks.
The carbs would be a good thing to have a look at, Maurice, how difficult is it to take them off and perform said operation to them?
So apart from the air box, carbs, exhaust and plugs, am I right in saying there shouldn’t really be much else to look at?

Killa
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[EuropeanNC30R...]

Tbh I've never tried, they're supposed to be an absolute bastard to get back in place without a leak.

Don't suppose you've already tried running it in on redex?

Also, does it happen more on a emptier tank than a fuller one? A very common problem is the fuel taps vacuum pipe become detoriated and causing the tap to not let enough fuel through.

It's fairly easy and free to convert it to the hrc spec gravity-fed tap. (You just take some bits out of the fuel tap, and re-arrange it).

[killa]

At the weekend I took apart the tap, cleaned it through, must admit a slight improvement but still a niggle.
The lines and the tap itself all look in good condition, diaphragm etc…..
I’ve used 2 rounds of redex, its all a little improvement, only a bit though.
Hmm, sounds like it could be an on going thing…..
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[NC30UK]

Import bikes run lean compaired to UK bikes. The jetting in the carb is different to keep the power down. Putting a race can on kills the mid range and knocks down peak performance a little bit.

Import jets:

110 front
110 rear


UK spec:

115 front
118 rear

Putting a race can on requires rejetting, and yours being an import was underjetted anyway!

You can buy 4 jets of 120 size. These will sort out your power. Putting 0.5mm thick M3 washers under the carb needles will sort out the massive flat spot from 5500 - 7500 rpm. i suggest 2 on the front, 3 on the back.

If the carbs arn't balanced the throttle response will and jerky and irratic only providing decent results when all the way open.


The carb rubbers on vfr' are a sod for going as most are getting old now and they take alot of stick when you take off/put on the carbs. the clips around them are also very hard to do up, especially the front right cylinder. you need to go to halfords and buy a 30cm long cross head screw driver to do them up with, leaving them loose makes an air leak.

[EuropeanNC30R...]

The jetting also depends on the model for the import bikes. The 89-91 (R) non-adjustable forks model was leaner than the 91 onwards adjustable forks and remote-reservoir rear shock model (R3).

I have an R3 and an R at home in the garage, both imports with race cans and run fine, I doubt the jetting here is the problem.



Imho 120's and that amount of washers sounds way too rich for just a can, I was recommended by someone who builds these as race bikes to go for 120 main jets and one washer under the needles for a full race system.

[NC30UK]

Rick Oliver told me to do what i've done and it works pefectly.

[killa]

I think this is the reason I’ve never got to the problem.

Thanks anyway guys, I’m going to have a word with my mechanic.
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