Float level

[bufallobiff]

Has anyone checked the float level on their 125 carburettor by using the method described in the shop manual? They tell you to use the drain tube and raise it above the carburettor and open the drain screw. With the drain line higher than the carb, you can use it as a guage as the gasoline seeks "it's own level" and will indicate the level in the bowl. I have adjusted the mixture screw seven ways til Sunday and still cannot get the carb to operate properly. I was hoping that someone may have done this and can offer me a base line to start with. I did it accd. to the manual but the book is a little vague and I'm really still not sure that it's correct. If I can get this right and go back to 1 1/2 to 2 turns on the screw I hope that will fix me.

Thanx

[djsbriscoe]

Hi,
The problem with trying to use the method in the manual is that the carb has to be level. This is nearly impossible to achieve unless you have the whole bike on a stand that can be adjusted. As the carb is mounted on a downhill angle this would mean you have to tilt the whole bike backwards or lift the front wheel up to get the carb level.
I too have had problems with the idle mixture and I removed and reset the float level several times. I set it to 19mm, result engine ran worse. Set to 22mm engine would not idle at all. The conclusion is to set the float level to 20.5mm (midway between 20 and the max 21mm setting) using a setting tool (available on ebay) and a digital vernier caliper. I have also replaced all the steel jubilee clips on the intake,aircleaner and crankcase ventilation hoses with nylon herbie clips.
These do not expand when hot and therefore do not allow any air to leak into any small gaps. These gaps are formed because the jubilee clips are not completely round, whereas the nylon clips are. Look up herbie clip on google to see what I mean.
I am now awaiting a motion pro idle screw adjust tool so that I can adjust the air mixture properly. I still have a problem with fuel filling the overflow pipe but if the idle mixture is adjusted properly the fuel in the pipe should have no effect, (I hope).
I will let you know what happens when I get the tool.

David.

[bufallobiff]

Herbie clips, eh? I've been using them for years and had no idea that's what they were. Ice machine manufacturers use them to fasten their tygon hoses. I ordered the idle screw tool on your recommendation as nothing else I've tried works. They put that screw in the worst place possible. For such a small and relatively simple carburettor, it is a pain in the ass. I bought this bike used and it runs like the wind as long as there is a load on the engine. Unfortunately, you can't accelerate all the time. It starts with no problem and I can ride it as long as I get on the highway right away and open it up. I,ve been able to loosen the clamps and give the screw a quarter turn at a time but I think my problem lies elsewhere. If I could get some one whose bike runs properly to measure their float level using the manuals method with their bike level, I could, at least have a starting point. I have often wondered if there was a CV carb that would fit this bike. I can fix them.

[djsbriscoe]

Hi,
If you loosen the clamps you will get air/vacuum leaks.
If the bike runs ok it's best to leave the float level alone. If you really must check it, the best way is to remove the carb and set it as per manual specs with a digital vernier caliper and a carb float height tool (just look on ebay). I considered trying to set the fuel level dynamically but the problem is orienting the carb (not the bike) so that it is completely level.
If you look at how it is positioned relative to the engine it is pointing in a downhill direction.
Anyway even if you did use a plastic tube this would only give an indication of fuel level, you would still have to remove the carb and reset it if needed.
If you find a way of using the method used in the manual let me know how you did it and if it works. Just setting the float height to 20.5mm I feel is the best solution.

David.

[djsbriscoe]

In reply to my previous post MotionPro Pilot Screw Adjusting Tool (part number 08-0119) DOES NOT FIT as there is insufficient room for the curve of the tool.
I am going to order CARB TOOL 90 DEGREE W/BITS (Part # 08-0229) from Off Road Only in Wales and experiment with various hex and 1/4 inch bits.
I will post my experiences and results in this post.

David.

[bufallobiff]

I left my float level alone after doing it accd. to the manual. I finally got proper throttle response by going full rich on the slide needle. I put it on the fifth slot and it runs perfectly.