• Welcome to the forum website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Online Forum Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this forum website.

    If you have previously registered to use this forum website, you should log in now. CLICK HERE.

    If you have never registered to use this forum website before, please CLICK HERE.

Main Jet for 928 consentrics

tjcassar

Well Known and Active Forum Website User
Non-VOC Member
I am sure not to be the first to fit a set of 928 consentrics on a Rapide. Well I have just fitted a pair and am not getting the performance expected.

What is worse is that at high speed, 80MPH plus on forth gear, the engine stops pulling and starts misfiring.

Once I remove the plugs for inspection, I find the front one sooty whilst the rear one is perfect. Settings are as follows: Main jet 260, pilot 30, needle jet 106, Valve 3. for both Carbs.

Would one be correct in trying a smaller main jet for the front cylinder only?? Or would it be wrong to have different settings. By the way the needle is right down so can not set it leaner for both carbs. Any help suggestions appreciated.
Tony
 

mercurycrest

Well Known and Active Forum Website User
VOC Member
Hi Tony,
I've got 930's and they use 180 main jets. I can't see where 260's would be anything but rich. I'd think 170 or 180 would be a good start.
Happy Hunting, John
 

tjcassar

Well Known and Active Forum Website User
Non-VOC Member
Hi John,
WOW, that is such a big difference. I got my carbs from Surrey Cycles and they were supposed to be set for the Rapide. Suspecting that this could be the cause, I ordered some smaller jets which I am waiting for. I ordered a pair of 200's and 230's so it seems that I am still far out!! So I will try the 200's and see how I go before ordering a set of 170's and 180's.
Thank you for your advise.
Tony
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
Hello Tony, I would say 210/ 220 if you have mk11 cams and open exhaust, But those slides seem rich, I am running near to 4. Good Luck Bill.
 

tjcassar

Well Known and Active Forum Website User
Non-VOC Member
Hallo Bill,
I have just received new jets from Surrey Cycles ( They supplied the new Carbs) I got 2 off 200's and 2 off 230's. am trying the 200's first to see how I go with these and take it from there.

I do not know what cams I have, but mine is an early Rapide C so whatever those come out with are fitted on it. I have a silencer on my exhaust pipe so its not an open exhaust.

If this fails, I will then have a go at the slides.

Thank you for your contribution.

Tony
 

tjcassar

Well Known and Active Forum Website User
Non-VOC Member
Hi John,
Tried out the newly received jets 200's. worked perfectly and no more soot!! no more misfiring so that was the problem. I can probably improve things a bit later but for the time being the set up seems fine. Thank you for pointing me in the right direction.
Tony
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
Hello Tony, By open pipe i mean silencer with a big hole, ie, not spiral inside. Good to know it's going better, Cheers Bill.
 

tjcassar

Well Known and Active Forum Website User
Non-VOC Member
Hallo Bill,

I had a look at my silencer and it seems to have an obstruction inside it. not a big hole but a fairly small one out of which the exhaust comes out I suppose!!.

My thinking is that its a proper silencer with some sor of partition inside. I can not see what there is but certainly not an open pipe or large bore. Its about 3/4 of an inch in diameter.

Well, yes as I reported, I did go out for a spin this morning after changing down from 260 to 200 main jets. The bike sounded and felt better and the plugs once inspected were the correct colour.

This has proved that it was certainly too rich and that what I need to do now is get the correct jet size. I also got a set of new 230's so I might try those too as top speed seems to be an issue as I can not go over 95mph on top gear. Having said this, it goes very well on all other three gears reaching 75mph on third gear so I might need more advise to obtain better Autostarda performance.

Mind you, I have one of those gearboxes with a very long first gear!!

Cheers and Thank you for your help.

Tony
 

mercurycrest

Well Known and Active Forum Website User
VOC Member
If this fails, I will then have a go at the slides.

Thank you for your contribution.

Tony[/QUOTE]

Tony,
If you decide to try leaner slides, you may have to raise the needles to get mid range fuel/air mixture back in sync. I think #3's with the needles in the lowest position are good to go. You're probably still too rich with the 200's. Is there anywhere you can just borrow a supply of jets? 75 in third isn't all that good. The "small" hole you're looking at in the silencer isn't the tube the Spiral is wrapped around is it? There were a bunch of Spiral Baffle copies that were crap, that could be a big part of your 95mph top speed.
Cheers, John
 

tjcassar

Well Known and Active Forum Website User
Non-VOC Member
John,
So, it seems that my silencer is not the correct one!! where should I get a proper one which will work well for me? Any suggestions?

Slides, I will work with the 3's for now and experiment with jets. Unfortunately in Malta its impossible to find anyone with a stock of consentric carb jets. Plenty of Pre monoblock available but not the ones we want. Its not a big deal as I can start a stock of them!!!! what should I go for?? 180's and 190's??

I wiull start with the silencer change then go for a smaller main jet

Cheers
Tony
 
Warning! This thread is more than 12yrs ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Top