TY 175 hard to start

[Takhli44]

I have a 1980 TY 175 That is hard to start after not being used for a few weeks, starts good (2-3 kicks cold 1 kick warm) when used regularly. It starts right up when pre mix is squirted into spark plug hole or carb intake. Same issue with a different carb. When it starts after sitting weeks it runs very lean for 30 seconds to 1 minute before it will take throttle, once it takes throttle it runs normally. It has Boysen 2 stage reeds and is .5mm oversize. I'm thinking perhaps leaking reeds or crankshaft seal until it warms a bit?
Spark is hot and blue, timing is .070 inch BTDC as per factory spec. Can see fuel move toward carb when fuel is turned on. Fuel enrichener (choke) seems to work properly.
Any suggestions that might point me in the right direction before I tear into it and start looking around?

On a separate issue, should the fork tubes be raised in the triple clamps?

[David Lahey]

Yes I get a similar effect - I have a few bikes that run very lean on the pilot for a while after being started following an expended period without being run. There is always a short period when starting a motor before it warms up that it is lean on the pilot jet, but when it takes 2 or 3 minutes of riding before the flat spot disappears, I suspect that the light fractions of the premix evaporate from the float bowl contents during the time it is parked up, and leave a gooey residue behind, including inside the pilot jet and pilot jet passages, which then gets washed out as fresh fuel flows through the pilot jet passages.

You could prove or disprove this by draining the float bowl after a ride and testing what happens after a few weeks. If you drain, there will be far less gooey residue.

The height that the tubes are set at on a bike are a personal thing, but I can say that the standard setting for TY175 forks on a TY175 is 22mm of fork tube protruding. Lots of people run with them flush with the top clamp, for various reasons, and some run with them protruding through further than 22mm.

[Takhli44]

Thanks David, the gooey gas makes a lot of sense. I'll do some testing as you suggest by draining the float bowl. Thought I read on here somewhere about the 22mm as a stock height thanks for confirming it for me. I have played with that on another bike (RL 250) and that seems quite a lot. I could tell a difference with just a few mm rise however I'm going to start with the 22 mm and go from there. Some folks have switched to MX 125 triples which have the tubes aligned with the steering head for these bikes to reduce the fork angle. Raising the tubes should do the same perhaps to a lesser degree without altering the already pretty short wheelbase.

[Jon V8]

I always drain the float bowl on my TY250 before using it.As it now has very little use,( I tend to ride my Pre65 bikes if I can) I often find a small amount of water hanging around.As indeed I do in any of their carbs.I wonder if its down to the Ethanol content in the fuel,as I'm very careful when washing them off after a trial.(Ok,often I cant be bothered/don't have time...)
I guess the damp,cold conditions here make the situation worse, as the hot conditions in Australia could easily make the evaporation of the high ends much quicker.Different conditions,different residue in the carb - but the same result when you want to start and run the engine.

[Takhli44]

Thanks Jon V8, didn't know you used ethanol blends in the UK, we have a choice here in South Dakota, USA and I choose to use non ethanol in all my bikes and small engines. I have not found water in fuel for years. I suspect we may not have that choice much longer.

Dry (semi arid) climate here as well.

[David Lahey]

Yes Jon we are also lucky here in Australia, being able to choose to buy pump petrol with or without ethanol.
I have tried pump petrol with ethanol a few times in some two stroke trials bikes as an experiment and find it tends to make them run too lean, so tend to stick with the petrols without ethanol.

[TriCub]

Your fuel question has been answered. But using different streeing clamps will not alter your steering angle it will only change you trail. The steering angle is fixed by the frame but it is changed if the frame attitude is altered by lifting or lowering either end. If straight clamps are used you will increase the trail making it more stable in a straight line but a little heavier to turn.

[Takhli44]

TriCub, thank you for the reply,I'll use wheelbase here to try to explain myself as I'm a bit confused. The straight fork clamps will give me less wheelbase than the stock ones and a closer to vertical fork angle, I would think this would give less trail? Do I have it backwards?
Think I need to amend an earlier post from "steering angle" to fork angle thanks for bringing that to my attention.

At any rate I'm going to mess with the fork tube height and see what feels best in the seat of my pants, nothing I can't reverse.

[TriCub]

Yes you have it backwards. It will increase the trail.

[Takhli44]

Thanks TriCub, you and others have given me a lot of useful information over the time I have been on here.

http://bikearama.com/theory/motorcycle- ... explained/
Found this on the web after reading your last post here, it explains it pretty well and the diagram makes it really clear where I had it backwards. I was having a hard time getting my head around that.