Vince
New Member
Posts: 28
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Post by Vince on Jan 20, 2023 22:40:41 GMT
I have a problem with my 1H 4 stroking when the throttle is half open. It's fine on full throttle and fine on closed throttle but not so good on partial throttle. Any suggestions on how to improve this. Makes it uncomfortable to ride when you can't maintain a cruising speed.
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Post by lostboy on Feb 7, 2023 16:24:35 GMT
I have a problem with my 1H 4 stroking when the throttle is half open. It's fine on full throttle and fine on closed throttle but not so good on partial throttle. Any suggestions on how to improve this. Makes it uncomfortable to ride when you can't maintain a cruising speed. Hi Vince, it could be caused by numerous things. However, with modern fuels do you use E10? Quick and cheap alternative is to top up fuel with E5 Super grade fuel or ethanol free fuel you can purchase and local suppliers. Is the jetting in the carburettor standard? Reiner |
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Vince
New Member
Posts: 28
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Post by Vince on Feb 9, 2023 14:07:01 GMT
Reiner
I use E5 super grade. I did drop the needle one notch but perhaps I should have gone the other way. It is a pain working on the 1H carb as it has a ally cover over it which can't be removed unless you loosen the tool boxes. The cover includes the air filter also. I know some people remove the cover and throw it away!
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Post by lostboy on Feb 9, 2023 16:47:09 GMT
Reiner I use E5 super grade. I did drop the needle one notch but perhaps I should have gone the other way. It is a pain working on the 1H carb as it has a ally cover over it which can't be removed unless you loosen the tool boxes. The cover includes the air filter also. I know some people remove the cover and throw it away! How old is the fuel? Ethanol attracts moisture out of the air which is no good. It's actually cleaning your tank and all fuel lines so you might have dirt in the jets. I have terrible problems with E5 if I don't use the bike regularly. If you say you dropped the needle one notch you actually have to raise the needle to provide more fuel in mid range. |
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Vince
New Member
Posts: 28
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Post by Vince on Feb 10, 2023 14:33:38 GMT
Always fresh fuel. I'll try raising the needle and see if that helps. Thanks for the advice.
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Post by Rex1932 on Feb 13, 2023 18:20:23 GMT
Hi Vince.
If you bike is four stroking at part throttle the mixture is too rich. This could be due to an incorrectly set throttle needle, a worn needle jet or throttle needle, high fuel level in the float chamber, too much oil in the two stoke mix or possible due to modern fuel being a different composition to the fuel it was set to run on.
The carburettor on your 1H engine should be a Villiers S25/4. The throttle needle in this carburettor is adjusted by a screw in the top of the throttle slide that pushes the needle down against a spring. The factory setting is that the needle should stick out 1.9" from the bottom of the throttle slide.
Please be aware that Villiers used a number of different needle tapers in their carburettors so check that yours is fitted with the correct 3½° taper needle.
The factory carburettor settings are:
Carburettor: Villiers S25/4
Main Jet: 120 cc
Pilot Jet: 35 cc
Throttle Valve Cut Away: No 3
Throttle Needle Taper: 3½°
Throttle Needle Set Out: 1.9"
If everything is correct adjust the screw to drop the needle about 1/16" ( 0.0625") to give a needle set out of around 1.9625". If you do not have anything accurate to measure with, just under 2.0" should be OK. I have quoted 1/16" because that is the distance between needle grooves on Amal carburettors.
Test ride the bike and see if it has improved the mid-range running. If it is still rich you can make another adjustment and go to about 2.05" needle set out. I think that will be about the limit of adjustment on the needle. If it is still four stroking you will have to invest in a new throttle needle and needle jet. They are hopefully still available from Villiers Services.
Best of luck.
Rex
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Vince
New Member
Posts: 28
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Post by Vince on Feb 14, 2023 9:10:50 GMT
Thanks for the advice and clear explanation of how to set the carburettor and needle up. I'll give that a go when I have a moment - especially now as better riding weather is beckoning. I have had the bike 6 years and it's been on a consistent path of improvement!  I'll let you know how I get on. |
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Post by Rex1932 on Feb 14, 2023 15:04:31 GMT
Hi Vince
Fortunately I have a photocopy Villiers Mark 1H engine manual so the information was at hand. My area of interest is the pre-war deflector piston engines. The Villiers carburettors on the larger capacity engines have a bowden cable operated mixture control lever on the handlebars that moves the throttle needle up and down against a spring. So you can adjust the mixture as you ride along.
Regards
Rex
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Vince
New Member
Posts: 28
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Post by Vince on Mar 16, 2023 18:34:59 GMT
Rex
Well today I got around to implementing the needle settings on the James Colonel 1H Villiers engine. The set-out was well short of the 1.9625" you mentioned. I had to screw the needle down at least 3mm, might have been more. (Sorry, mixing units!) I thought - that can't be right, surely it can't be that far out!? So I did it anyway, reassembled and went for a trial run. Well I COULD NOT BELIEVE the difference! The 1H ran like a sewing machine at all throttle openings without any hint of the irritating 4 stroking at half throttle. Bike is nice to ride now and seems to start easier too. Thank you so very much for your advice!
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Post by buttybach1932 on Mar 17, 2023 21:21:06 GMT
Hi Vince
Very pleased to hear that the needle adjustment has sorted the problem with your 1H. Getting old bikes to run nicely makes them so much more enjoyable to ride. I have now joined the forum as a member so my log in name has changed.
Have a good riding season
Butty Bach
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Post by 1951superlux on Apr 11, 2023 19:17:54 GMT
Hi Vince.
If you bike is four stroking at part throttle the mixture is too rich. This could be due to an incorrectly set throttle needle, a worn needle jet or throttle needle, high fuel level in the float chamber, too much oil in the two stoke mix I think it's less oil in the mix, rather than too much that can lead to 4-stroking. Too much oil makes the fuel slightly more viscous and means that there's a bit less petrol in the fuel mix, both of which tend to weaken the fuel/air mix. Particularly with those engines where the book says to use 16:1 mix and you're actually running on 25:1, it pays to drop the needle a fraction. Of course this isn't really relevant to the original post ... which is sorted now anyway! |
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Vince
New Member
Posts: 28
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Post by Vince on Apr 12, 2023 12:17:17 GMT
I do run at 20:1 but I know some people go out to as much as 30:1. I guess that could make a significant difference.
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d7er
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I'm not that new, I re-joined four years ago. I volunteered for the south Northamptonshire area rep'
Posts: 46
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Post by d7er on Jul 25, 2023 11:30:28 GMT
More oil in the fuel means that it's thicker and takes longer to pass through the jets, whereas the same amount of air is being taken in constantly, so engine runs weaker.Maybe a too simple a solution at face value, but I feel it's not far off.
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I'll let you know how I get on.
