TM24 issues (should I go to a PHBL25?) - help please!

[dansuper]

Hi all,

I'm currently running a Casa 185, KBA clubman, K&H high flow filter and TM24 - and simply can't get it running happily. I previously gave up on a PWK24 with the same configuration due to being so frustrated with the symptoms.

I've tried both the 4DHL and 5N17. The 4DHL is obiously leaner but is also much 'shorter' than the 5N17, which has a taper that extends about 5mm further. How would this impact overall performance? Either way, the scoot seems to be running too hot through the mid range, and when when I move to richer needle clip position it becomes really boggy from about 1/8 to 1/4 throttle. 1/2 to WOT seems fine and it pulls very hard without ever really breaking up at wide throttle openings.

Residue around the pipe is basically oily and wet as if it is running really rich - no matter which settings.

Current spec. on the carb is 5n17 at second clip, 17.5 pilot and 180 main. This is far too boggy low down, but when I compensate for that it just seems to run hot with a very pale plug.

I've tried combinations with both needles, mains from 170 to 190 and pilots from 12.5 to 20. Completely lost and confused. Oh, and it's currently set at 20 degrees BTDC.

I'm seriously thinking of going to a PHBL25 and running a standard or BGM mesh filter set up, just to see if I can find satisfactory performance all round and cooler temperatures.

Any thoughts would be appreciated - and can anyone recommend a set-up start point on PHBL25s for the above spec - in case I make the move?

Thanks!

[bazman]

Have you tried altering your timing? Come down a couple degrees? Carb does sound rich at them settings, also compression ratio?

[DaveTomo]

If you go for the delly,I think a lad on here stoneislandv8 runs a casa185 but with a delly 26 could be worth dropping him a PM ( http://scooterotica.org/forum/viewtopic ... 2&start=40 thats his dynograph) .Mikuni's are good carbs ,but saying that I could never get TM24 set up right on mine,same as yourself,either too hot or rich so I gave up and put a delly 30 on.BUT a lot of people swear by them,throttle response,fuel consumption etc. could be worth a look in the carb set up section to see if anyone else is running a similar set up.either way good luck.

[Lamaddict]

I kept hearing how much better Mikuni's are then Dellorto so I started using Mikuni's for a few scoots without any great success but on my latest scoot I'm back on Dellorto and find it much better. I did have a 25 PHBL on but I've just gone to a 28 PHBH.

[CPH Lambretta]

I had the same with a TM24, could never get it to run right, I just gave up in the end.
I have a brand Phbl 25 for sale, PM me if your interested.

[sideout]

I'm a fan of the Mikuni TM24. I run one on a Mugello 186 v4 through the airbox (neck removed) and a KBA Clubman. I find the following jets spot on: Pilot 17.5, Main 180, Needle 4DH7 clip 2. Gearing final ratio 1:5.

(I presume "4DHL" in your post is a typo for "4DH7"?)

[ArmandTanzarian]

I couldn't get rid of a lean spot when easing off at high revs with my TM24. Mind you I couldn't get rid of it with a 30mm delly either. In the end I changed the pipe and all was well. If I could be bothered I'd try again with the 24 Mikuni

[dansuper]

Have you tried altering your timing? Come down a couple degrees? Carb does sound rich at them settings, also compression ratio?

Cheers - yep, I originally had it at the standard 23 degrees but that was probably foolish. I'm willing to drop it further just to see what happens.

The spec I mentioned above is basically the richest I have tried, and it is indeed a pig in that state.

Compression ratio - it's never been measured but I've always thought it felt very high. I remember there were two head gaskets supplied in the kit, with one thicker than the other. I need to check which one I chose...

[dansuper]

I'm a fan of the Mikuni TM24. I run one on a Mugello 186 v4 through the airbox (neck removed) and a KBA Clubman. I find the following jets spot on: Pilot 17.5, Main 180, Needle 4DH7 clip 2. Gearing final ratio 1:5.

(I presume "4DHL" in your post is a typo for "4DH7"?)

Ha... yes, 4DH7. Must have DHL on the mind from deliveries from German scooter shops.

I am curious to run a standard filter set up just to see what happens, particularly as the kit is really meant to be bolt-on with no change to carb or pipe.

Thanks.

[red ghost]

Dan, don't be gay, your carb is fine..

Check your compression, then check it again then have a grown up check it..

As above with your timing..

Do you have a funny crank fitted?

Have you measured your port timings?

What plug are you running?

What happens when you run it without a filter?

Have an extended mixture screw fitted by any chance?

Talk with Benji and JP they also can help..

Try a 15 pilot and try a 4H16 or a 5K1 needle (Keystar items are fine to use, pm me if you want more info)

frank