CArb air leak

[Mick Hayward]

Hi Guys

I have a small problem with my ST. I've discovered that I have air leaks at the joints between head and carb rubbers on all cylinders. I expect they are original rubbes. Can some one please advise if there are replaceable gaskets between the rubbers and head. Or do I need to relace the 4 rubber mounts which are obviously distorted. I'd like to get the bits before I strip the carbs off again.

Thanks Mick

[zedrider]

as far as i know there is no gasget . clean the serfice or the rubber with emmry cloth or simular and apply some gasget sealent to the mateing serfice .

[Mick Hayward]

Hi Zed

Are the rubbes metal faced where they meet the head. If it is then there should be a manifold gasket.

Thanks

Mick

[zedrider]

i`m sure some one who knows more than i do will let you know . but ive never fited a gasget there the rubber its self forms the seal but if its leaking i would just clean the surface of the rubber . and then appy some sealent . its works for me . i cant remember seeing any gasgets in any of the full gasget sets ive bought . best wishes ian

[Mick Hayward]

Hi Ian

Thanks for this. Best I take them off and have a look. I expect they have bowed over the years. I'll try to face them off on a piece of glass and as you say try to seal them. If it doesn't work i'll have to get some new ones.

Cheers

Mick

[Mick Hayward]

Ian your a marvel

Firstly took carbs off and found that the carb mounts were not particularly tight. Took them off and its obvious that they have seen better days, however I re-mounted them with sime loctite 5922 gasket goo, fitted carbs turned on petrol, pressed starter and hey presto. It bursted into life and settled at a tickover of 1000 rpm, no rough running or spitting. Stopped it and tried to start it and it did it again.

Perfect.

Now I can get on and sort the rest of the bike.

Thanks

Mick

[Al]

Mick, am i right in thinking that some while ago you posted a note about changing the std airbox for aftermarket filters?

If so you probably got the same problem as i had. The carbs are now un-supported and up/down like a whores drawers.

I had to make a small flexible bracket to boost the support given by the carb manifold rubbers to give a little lift and stop them vibrating the mountings to death.



AL

[Mick Hayward]

Hi Al

I did post that message. However never fitted the freeflow filters, infact never fitted anything. Main airbox has been disconnected too. Problems with the running prevented me from progressing. Now I have a choice. Standard or freeflows. I take your point about supporting the carbs and will look into that if I fit the freeflow filters. I would like to fit them but don't want to experiment with main jets too much. Have you fitted some and if so what main jets have you fitted. I certainly think it makes the bike look better.

Regards

Mick

[Al]

Mick mine came with Ramair filters on it when i got it.
The guy i bought if off (good friend) had never done anything to the carbs and it had had those filters on when he bought it.

By the way it has standard CV's and its a J1

He was told and i have since heard that you cant get the carbs correct with those foam filters (Ramair's)and not to get too technical i think that opinion may be at least correct in some ways.

Steve Debben suggested that the best available reservoir of laminar flow is achieved with the OM air box.

This may or may not be so for slide carbs, i wouldnt know.

All i can say is that at full chocolates i have had the impression that the vacuum slides are oscillating up and down and giving a surging rather than linear power delivery. This after fitting a support bracket.

On the subject of jetting; ironically.... the last time i rode it, it was a f&*^%$g animal. It scared the cr^p out of me!
Mixture was a little weak of perfect mixture strength (point at which maximum horsepower is developed) and is currently running 130 mains and needle position is No.5 (clip at bottom of needle (richest setting))
This is standard 998 with standard cams, and premium unleaded. Timing is 2 degrees retarded from factory and its complicated but i wont mention the stage 3 dynajet kit because it's not actually there!!!!

All in all i would say that its too much darn trouble messing around for me and i wish to god someone hadnt buggered around with mine in the past. But it is what it is and i have been following a long slow path back to somewhere near standard.

That said i have just had it bored to 1170 and fitted a bigger valve head and higher lift cams so who am i to talk.
Oh and it should now have brakes for the first time since iv'e owned it!!
I shall follow my own advice and let the dyno boys set the mixture and jets when it's run in.

Hope this is of some use.


AL

[zedrider]

i`m glad shes now running better . i`m sure you will have her behaveing :-) took my zed out today just a quick blast in the sun :-) best wishes Ian :-)

[Mick Hayward]

Al

Standard it will be. I just need some carb to airbox rubbers to suit the ST. Apart from that I have a siezed rear caliper to sort out.

Mick

[Al]

Mick, i'm not trying to talk you out of doing what you want to do but one other thing may be worth mentioning in this evaluation.
In theory, at least all four freeflow filters should get dirty at the same rate and deteriortae at the same rate. What i hadnt bargained on was when i took them off for the last time i discovered that the bottom of two of my Ramair filters had disintegrated and had proper holes in them!!EEEEEEK Big proper holes at that on the underside.

I knew they were old but i hadnt figured that one.
Guess what i'm trying to say is that with one filter you know when its done and all carbs get the same air for better or worse so to speak. I'm sure that i had been adjusting the mixture ad-infinitum to offset this problem as it developed but without having the awareness to look into it further.



AL