Carb jets.....

[Collywog19]

Just realised my old airbox has a k and n filter, also wondering if the old carbs got sorted too.

So basically im after info on standard jet sizes etc to find out if mine were done, instead of taking new carbs off bike again just to compare jets.

Thanks

Col

[Collywog19]

Bike is a 1997.

Col

[sirch345]

According to the manual the standard jets are:-

Pilot jet for (1997 model) 45

Front carb main jet 175

Rear carb main jet 178

Chris.

[tony.mon]

Mmmmm. I wonder why different sizes front and rear?

If it's because the intake trumpets are different lengths, maybe I should have rejetted when I put two long ones on....

Any ideas?

[Collywog19]

Right guys.

Just took old carbs apart and both mains were 190.

I think i remember a couple of washers underneath the needle on the rear, when i took it apart.

Should i stick these jets and k and n back on bike and maybe it should run better?

Tony, i have no idea why diff sizes, as u say could be because of trumpet parts.

Thanks

Col

[warby221]

Jezzzzz 190’s are to big I’ve got straight through exhausts and a K&N filter and have 185’s cant remember the needle position exactly but the back is two notches lower

The difference in size is to do with the front cylinder running cooler than the rear “so I’ve been told”
The 190’s are the biggest size you get in the dyno jet kits

[Collywog19]

Ahhh i seee

well my cans are now stubbied so maybe 190 should be ok?

i can easily buy some 185 jets if you guys think it will be better.

Col

[warby221]

(Try a plug chop)

Run the engine till its at normal temperature on the road get it up to 9k rpm ish then hit the kill switch and coast to the side of the road (this freezes the engine at its last running condition) take the plug out and have a look

If it’s sooty it’s to rich -------washes the oil off the bores wearing them out

If it’s grey all over it’s to weak -------causes overheating and pre-detonation melting pistons and seizures in extreme cases

If it’s brown round the outer edge and greye brown round the porcelain its about right

If it’s oily you need a new engine lol

To tell you the truth its better to stump up the cash and get it on a rolling road and get it set up properly

[Collywog19]

Just fitted the setup it used to have on it.

It had propper needles in old carbs too.

so its 190/190 , dyno jet needles, and k and n filter.

Taking it for a run out shortly, But i will invest in dyno time very shortly

Col

[Jonesey]

Hi all, does 2 long trunpets have any effect on fuelling?
Just wondered if it made any difference to low to mid range?
Thankyou kindly, Chris.

[Seven Of Nine Firestorm]

Jonesey are you talking about the intake trumpets, where the buttely valves are, hey if you wanted to get them bored out for max sucktion that should also help with better breathability.

[Jonesey]

Yep, i mean the intake trumpets in the airbox, i've got 2 long and 2 short, so i can make any combo.
Just wondering what, if any effect changing these for other combinations has on the bike??
All input welcomed.
Cheers, Chris.

[tony.mon]

There's been a thread about this:
http://www.vtr1000.org/phpBB3/viewtopic ... it=trumpet
should get you there.

I have played with this, and can confirm that two long ones makes the lower/mid stronger, playing into the strength of the engine and power delivery, at the expense of a little top end. I most definitely noticed the fatter midrange, and couldn't tell that the top end was missing anything.

So if you often sit in 5th flat out waiting for more, then fit two short ones, but if you use the engine grunt then two long ones is the way to go, IMHO.
If you want both, then one of each is the standard Honda compromise.

I went to the Bulldog last year with two sets of trumpets intending to dyno it and run the strip with all three combinations.
However, due to rain most of the weekend I only got an 11.6 and 106 on the dyno with two long ones, and then didn't get a chance to try the others.

This is with carbon can co straight-throughs and a K&N, with a dynojet kit but according to the dyno readout it's running lean mid-range, so there's a little more to come once I've set it up for this year's Bulldog.

To be honest, it's the bloody clutch that stops fast launches, not which trumpets you have on.

But go play, and let us know what you think.

Oh, yes. Boring them out?
Might work, but they're thin plastic so there's almost no advantage to be had, but I've definitely seen nice aluminium ones somewhere, at an extortionate price.....

I'd love to try a set of variables lashed up from an R1 set, or MV ones- can't take much chopping and hacksawing to make them fit?

[Seven Of Nine Firestorm]

Got the spare set of carbs many thanks to Tim.
Before I can find someone to bore them out for me then new butterfly plates, noticed under the butterflies there is a sheet of metal almost all the away across which to me significantly would interupt and starve air flow, has anyone tried to take this plate out under both butterflies and have it free flowing for maximium suction. ? What is the purpose of it.