Concentric Mk1 Fuel Starvation
- Thread starter b.l.hayward@tesco.net
- Start date
Hello i had some good results tuning my Mk1 by following the three steps
described on this page:http://www.performanceindian.com/VinAmalMods.html
greetings Karsten
described on this page:http://www.performanceindian.com/VinAmalMods.html
greetings Karsten
Thought it was about time I updated on the thread...Still no absolute solution, BUT the twin runs ok when not on pilot - still seems to tick over periodically on 1.5 cylinders 'till I pick it up on the throttle (have played with pilot air setting and throttle stop according to KTB). But what I HAVE found is that if I remove the pilot jet from time to time the hole in the jet seems to be blocked with a small,spongy blob the size of a pinhead - a bit like Evostik that has gone off in petrol. Now I had my tank fully refurb'd....tank sealant? I also took out a petrol tap and a larger blob of the stuff was wrapped around the top of the thread.This is my current thinking so I am hoping that the passage of time will eventually stop disolving off the inside of the tank which I know was coverd with seal during the refurb.!
impossible to flood with brass float needle
It became unworthwhile trying to start my Comet a while ago. I have just recommissioned it with a resleeved barrel and low expansion piston. It has been extremely hard to start and changing to a plastic float needle produced an overflowing carb. For MoT yesterday I turned the petrol on 2 hours before I wanted to use it. After kicking for quarter of an hour I made a clip to hold the tickler down but it still wouldn't flood so I changed float chamber/float and needle to use the complete plastic needle set up. It left a big puddle on the floor but did become startable. By the time I got to the MoT it seemed to have settled to working OK and today it is behaving exactly as it should. Turn petrol on - tickle for two or three seconds (until flooding visible) - Start first or second kick. I have ridden it every day this week and this tip from Sidmadrid seems to have turned it into a rideable bike. Many thanks! Ian
It became unworthwhile trying to start my Comet a while ago. I have just recommissioned it with a resleeved barrel and low expansion piston. It has been extremely hard to start and changing to a plastic float needle produced an overflowing carb. For MoT yesterday I turned the petrol on 2 hours before I wanted to use it. After kicking for quarter of an hour I made a clip to hold the tickler down but it still wouldn't flood so I changed float chamber/float and needle to use the complete plastic needle set up. It left a big puddle on the floor but did become startable. By the time I got to the MoT it seemed to have settled to working OK and today it is behaving exactly as it should. Turn petrol on - tickle for two or three seconds (until flooding visible) - Start first or second kick. I have ridden it every day this week and this tip from Sidmadrid seems to have turned it into a rideable bike. Many thanks! Ian
fuel starvation/concentric
You seem to have tried a lot of "answers" now try a silly[simple one] make sure that the breather hole in the fuel cap is not blocked with polish or other detritus. It's surprising how many folks get caught-out on this one. Roy.
You seem to have tried a lot of "answers" now try a silly[simple one] make sure that the breather hole in the fuel cap is not blocked with polish or other detritus. It's surprising how many folks get caught-out on this one. Roy.
I think you have probably solved the problem yourself,
I've had similar in the past and all down to minute bits of "gunge" blocking small fuel-ways, however I'm not sure about the "dissolving off", you refer to, as all the petrol sealing compounds I've ever used and there have some different makes, in different bikes, all needed to "cure" before adding petrol, the times varied, by ambient tmperature and actual application, I would not have expected any "bits falling off" afterwards, I wonder if there's something there worth looking at, as such small items can be major problems, untill removed.
Anyway, I've been running Mk1's on my outfit for fifteen years quite happily, without any major problem, although I did fit K&N filters at the original rebuild, I still think it was a wise choice, as there is very little wear on the slides, compared to the ones I replaced,
go carefully.
concentrics transformed
I know this is an old thread, but I came across it when searching info on Mk 1 concentrics. I fitted 32 mm carbs to my Shadow, some years ago, after Bob Dunn had ported the heads and flanged adaptors, but I never got it to run well. I had other problems, resultant of fitting Carrillo rods and not balancing the crank [32% balance factor, the vibration was evil], however, that solved and the bike back together, I carried out the mods referred to in both the "Bushmans carb tuning secrets" http://www.jba.bc.ca/Bushmans Carb Tuning.html
and "performanceindian". http://www.performanceindian.com/VinAmalMods.html
The bike is truly transformed.
If you don’t want to read the full details, I would briefly summerise.
Set the float levels correctly
install interchangeable pilot jets in the roof of the float chamber
drill out the fixed pilot jet. [Easier from fuel side, so fit blanking screw opposite air screw]
cut away the back of the spray tube
I used the basic setting recommended by performanceindian
Bernard Jones
Dorset Section
I know this is an old thread, but I came across it when searching info on Mk 1 concentrics. I fitted 32 mm carbs to my Shadow, some years ago, after Bob Dunn had ported the heads and flanged adaptors, but I never got it to run well. I had other problems, resultant of fitting Carrillo rods and not balancing the crank [32% balance factor, the vibration was evil], however, that solved and the bike back together, I carried out the mods referred to in both the "Bushmans carb tuning secrets" http://www.jba.bc.ca/Bushmans Carb Tuning.html
and "performanceindian". http://www.performanceindian.com/VinAmalMods.html
The bike is truly transformed.
If you don’t want to read the full details, I would briefly summerise.
Set the float levels correctly
install interchangeable pilot jets in the roof of the float chamber
drill out the fixed pilot jet. [Easier from fuel side, so fit blanking screw opposite air screw]
cut away the back of the spray tube
I used the basic setting recommended by performanceindian
Bernard Jones
Dorset Section
Carbs/Vibration
Hello Bernard,
Thanks for the tips on carbs, I didn't know I had a problem but I might have after grinding bits off them, !! I can't resist a tuning mod'.
But what about Vibration, My bikes have always had that problem, They have always had at least 9 to 1 pistons I know 7s are better but I like the extra grunt !, It didn't matter too much when I was young but with a bit of arthritis in the hands It's a Pain just hanging on !.
Can you tell us who fixed it and how much.
Cheers Bill.
Hello Bernard,
Thanks for the tips on carbs, I didn't know I had a problem but I might have after grinding bits off them, !! I can't resist a tuning mod'.
But what about Vibration, My bikes have always had that problem, They have always had at least 9 to 1 pistons I know 7s are better but I like the extra grunt !, It didn't matter too much when I was young but with a bit of arthritis in the hands It's a Pain just hanging on !.
Can you tell us who fixed it and how much.
Cheers Bill.