11 replies to this topic

[Somerset Steve]

Hi All.

I have been through my 200 as follows.
New. LT and Ht coils.
Re-built engine, seals, mains,ring, new air filter, pipe from filter to carb and carb to engine.
New delorto carb with 44 slow jet, AQ268 atomiser, 33D needle, 92 main,

Bike starts first kick every time, ticks over like a kitten, reves up ok to a point, however when nearing the top of its range it stutters and splutters and will not rev out clean. This becomes obvious when doing a hill climb, it runs out of steam in second and there is no way of getting going again.
Please can anyone think of a reason?
I am 99% sure the timing is spot on but will re-check if you think that could be the case.

Thank-you advance.
Steve.

[B40RT]

Something loose / moving in the exhaust and blocking it at higher revs / pressure ?

[treevor]

Try checking the float level, just cos thing are new we shouldn't assume their set right.
Sounds like it could be starved of fuel
T

[Somerset Steve]

Ta for that. I will check the float level.
As for the exhaust, i have cleaned out the mid box and fitted an new back box.

[Somerset Steve]

Anyone know what the float height should be?

[NickJ]

A bit basic but check you have a good flow of fuel to the carb. I have twice had the 'o' ring in the fuel tap jump out of it's groove and reduce the flow so that the bike ran OK until you opened the throttle fully for more than a few seconds.

[Somerset Steve]

Thank-you for the info so far.
Petrol tap fine.
Float level ok.
New plug.
92 main fitted as an experiment to see what happened.
All above have no improvement.
Rode an evening trial his evening, bike starts very well, at low and medium revs clean and well, but as soon as i open her up she has no go.
Played around with the mixture screw has some effect but wont get rid of problem.
Could it be the timing? I set it up using just the marks on the stator, if i use a dial guage on the piston at what point should the marks line up?

[NZRalphy]

Sounds like jetting to me.
If it is flat/no power when reving and a "Fwwwwwwwwaaaaaaap" sound is often running lean - so raise the needle and/or larger main jet.
Try raising the needle all the way (lower the clip) and see if it runs rich and gets a 'four stroking' feeling.

[Lee Harris]

I would put my money, and quite a lot if pushed, on the exhaust and silencer.

If it is crudded up, the bike will never rev out. And using caustic will just burn the carpet.

If the exhaust and silencer are choked up, they will feel heavy.

Start with the end can and cut it open and have a look. if not buy a wes although some say they are not as good.

On most fantics, they are 20 years old now, the main box will need cutting open and repacking as well.

nice piccie of a curt 300 exhaust on the classictriasl website

HTH

lee

[Somerset Steve]

Anyone know why the front exhaust box would be stamped FM250?
Also if i look into the air box from the carb side the hole into it appears to only be half open, at the top. There seems to a molding over 180deg of the opening from the air box to the pipe that the rubber tube goes on. Is this normal?
There are also 2 tubes that go up under the set off of the air box, about 25mm in dia. These appear to have had a hack saw cut them off much shorter.

Steve

[Somerset Steve]

Ta Lee,
However it seem you would have lost that money. Have fitted a new WES back box and cut open the mid box, there is now nothing in there and still the same problem.

I have increased the size of the main with no effect. What if i reduce it?

[ty250nl]

Hello,

Some simple things could be the reason:

Have you looked at the gascap of your petroltank.
If the ventilationhole is blocked it will create some sort of vacuum in the tank.

You will notice this at full throttle because of the greater demand for fule.

And is your carburator the right size?
A different diameter gives a very different response to gashand action.

Succes,
Arie