My Trabant and poor mpg

[Tyre Smoke]

Well there's a thing!

I'll invest in that I think.

[B'stard Child]

Tyre Smoke said:

Well there's a thing!

I'll invest in that I think.

But before you do that check the main jet and float height and set up to factory recommendations

We used to use the colourtune kits when tuning 2 strokes (porting cylinders, skimming heads, changing exhaust to expansion chamber ones and swapping carbs

If engine was stock didn’t use it - just start with factory settings and leave it alone save for tickover adjustment

[gazza285]

Did you check the float height?

You should not be starving the carb of fuel to get it to run right, find out why the carb is overfuelling...

[Tyre Smoke]

Yes, I know starving the carb of fuel is not the answer. But it does prove the poor consumption is overfuelling.

Not taken the carb apart today, had other stuff on. Job for tomorrow.

[B'stard Child]

Tyre Smoke said:

Yes, I know starving the carb of fuel is not the answer. But it does prove the poor consumption is overfuelling.

Not taken the carb apart today, had other stuff on. Job for tomorrow.

When you check the float height have piece of pipe attached to the fuel inlet and blow through it as you are checking the height - if it’s like most motorcycle carbs that really helps to determine the actual shut off point accurately

Also check the float needle valve and seat for any signs of wear or miss-alignment (I know it’s a new carb but it’s a new carb made to less than exacting tolerances) a 205 I had from new with a 35 IBSH carb had a really crappy needle valve and used to over fuel randomly until I replaced it with a viton tipped needle valve so even more modern carbs can be bad from new)

The 205 went from low 30’s mpg to high 30’s once I found the issue and corrected it - the Peugeot dealership failed multiple times to fix the issue while it was still under warranty.

[Tyre Smoke]

Luckily I declined to send the old carb back for exchange (€50 forfeited) so have all the jets, etc from it.

I do know from taking that apart before I got the new one, the float is supported on a spindle that is supported by two cast holes. Which sounds great, but there is enough play for the spindle to drift out of one and therefore jam the float.

[Tyre Smoke]

So after much head scratching and no idea what the problem was, I finally found out what the problem has been.

The choke wasn't fully closing. Sure, could push the knob fully in, but the lever on the top of the carb was remaining a third open. It wasn't immediately obvious but sometimes doing a job with two people is a good idea!

[AW111]

Good news.

[dontlookdown]

Good spot. So it was the carb after all - sort if anyway. Glad you have it sorted and tks for updating us!

[B'stard Child]

Tyre Smoke said:

So after much head scratching and no idea what the problem was, I finally found out what the problem has been.

The choke wasn't fully closing. Sure, could push the knob fully in, but the lever on the top of the carb was remaining a third open. It wasn't immediately obvious but sometimes doing a job with two people is a good idea!

Is the choke a "fuel enrichment" additional fuel feed or a "air flow restricting" flap device?

Makes sense if it's the former - not so much if it's the latter

[Tyre Smoke]

Yes, fuel enrichment. There's a lot less blue smoke now!

And there was me thinking choking cyclists was the norm. Hardly any smoke at all.