Triumphrat

johnquinnell · 03-01-2006

I'm just inquiring if any other single carb owners have a similar problem to me when their bike is nice and hot from a good run? I have a very stock TR6R 650 Tiger and both starting and normal idle is not a problem but when the bike gets nice and hot, the idle is a good 500 + rpm higher than previous. I have noticed that when I have finished my ride - 30+ miles, the single stock Amal carb is nearly as hot as the head probably because of the alloy manifold that connects the carb to the head. I was wondering if the effect of that type of heat would change the behaviour of the carb or the fuel in the bowl enough to cause this problem or maybe there is another issue I should consider?

GrandPaulZ · 03-01-2006

You should have a 1/4" thick fibre spacer between the manifold and the carb body BESIDES the paper gasket. I believe the gasket goes between the spacer and the carb, besides the o-ring in the carb flange.

It DEFINITELY makes a difference.

Lutz · 03-01-2006

johnquinnell
You may already have a warped carb body.You could have an air leak between the head and manifold or between the carb and manifold. Also check that the auto-advance is working freely.
A severe air leak can be cauasd at the carb if you put the paper gasket between the carb and spacer the gasket should go between the spacer and manifold.
I believe the 1971 TR6 does not use the 70-2968 spacer the carb is mounted with a thick "ring" that fits on the flange groove and not in the groove,the proper "o"ring is part#
70-9711.The one that comes in most kits is not correct and is to thin and fits into the groove.They also use two cup washers and rubber washers on the studs.When tightening the carb care must be taken to tighten evenly and tighten
leaving approx. 1/32 "gap between manifold and carb flange
Also make sure the "o"ring doesn't squeeze out.
This the proper way of mounting the carbs beginning in 1970 on the TR6 and Bonneville.
Lutz

tmiller11147 · 03-01-2006

Lutz is dead on with this info. for the '71. If you tighten the two bolts too much, the body flange will contact the manifold and overheat the carb.

Using one of the insulating blocks will improve the process. Just be real sure you don't over tighten or you will warp the flange and the body. If this happens, you will get slide sticking.

Tom

[ This message was edited by: tmiller11147 on 2006-03-01 20:43 ]

DAGAD · 03-02-2006

While I agree with you guys, sometimes the shoulder bolts that the carb fits on are too short for the 1/4" thick fibre spacer. The thick 'o' ring SHOULD be fitted and you could try using a tufnell spacer from a Norton. I have these from 1/16" up to 5/32" and use the one to suit a full nut on the stud.
#New cups and rubber washers are cheap and easy, but as the advice says, DON'T overtighten. You should be able to move the carb when correctly fitted.......... only slightly when wiggling it.
Roy.

johnquinnell · 03-02-2006

Thanks for your responses guys it all makes perfect sense now.
I've seen a similar situation in motor vehicle fuel pumps when the incorrect gasket isn't used but I never even gave it a thought that it could be a similar problem with my Tiger.
The carb to manifold gasket is nowhere near 1/4' thick (more like less than 1/8") so it looks like I'll have something else to tinker with this weekend. I'll post a response once I've checked out the gasket situation and get it back to what it should be.

johnquinnell · 03-06-2006

Just to update those readers who helped me with my overheating carb problem. I picked up the suitable parts from my local old British bike spare parts dealer for a couple of bucks. The original asbestos fibre gasket on the bike between the manifold & carb was pretty sad anyway. My Tiger now sports a new 1/8 bakelite insulator sandwiched by a pair of asbestos fibre gaskets + a new O-Ring on the carb body and new rubbers under the carb securing nut washers. Now problems with the old girl running fast when she gets warm now. Have included before & after shots for the benefit of some readers who may want to look at their single carb set-up themselves.
Thanks guys.
Before:
http://au.pg.photos.yahoo.com/ph/tri...cd.jpg&.src=ph
After:
http://au.pg.photos.yahoo.com/ph/tri...cd.jpg&.src=ph

[ This message was edited by: johnquinnell on 2006-03-06 14:50 ]