Hitchcocks Forum

Have recently fitted H's Universal Silencer to my bog standard 500 classic. Original downpipe, with restrictor, is still fitted. Have sealed everything with engineering silicone and upjetted accordingly, as per the catalogue: Mains:117.5 Pilot:27.5 Neddle Jet:PO. Hasn't really made any difference, still running weak from low throttle openings up to about 1/2-3/4, which is what H's book says, will cause bad running at these openings. At full bore or anything near it, it goe's like a Bullet, doesen't miss a beat. Plug is very light brown, engine temp appears unaffected, nan no noticeable blueing of the pipe. Might be as good as I can get it unless I can tweak it further. Will the (expensive)throttle slide upgrade do any good! Or do I need more (bigger) jets? Regards
Bullet Train

What groove is your needle on? Sounds like the needle needs lifting.

Throttle from closed to 1/2 approx uses a mix of pilot and needle, as the top end is fine it suggests your main is K, try raising the needle a notch, if you're on stock settings you should be in the middle of 5, so you have a couple of notches to try.

A quick reply at work. I'm on the standard No. 3 groove, shall raise the needle later and see what happens. As mentioned, once it's wound right up, it breathes like a Dragon and flies like a Rocket. Only replaced the (failed) "Torpedo" silencer with the Universal, cos' one came up for grabs, for £18, on this forum (cheers Durham Tim!). Just past 10:000km's last week and have not had it going like this before. Now sounds like a hybrid green laner? Slowly, getting it right I hope...
Cheers
Bullet Train

Don't forget that to RAISE the needle the circlip must go into a LOWER groove.....

Hello there Matey !!!! You still having problems ??? From what you're telling us it does sound like you are weak in the low to mid range. Remember that our hosts settings are only recommendations for a starting point---not the be-all, fix-it elixir-- so a little more patience won't go amiss. It would appear that you have the most important setting about right --ie the MAIN JET. The easiest adjustment is to put the needle clip into the No4 position and see how that feels...Do a test run and you may think that another move to the No5 position is called for...OK, now do another test run. If you still feel that more adjustment is called for then it's at this point you will need to change the pilot and needle jets to the next sizes RICHER---put the needle clip BACK to the No3 position---and start tests again...But by now you won't be far off the mark... The cut-away on the slide will alter the initial throttle response only. As regards to the main jet---my personal preference is that having got the plug to show a light coffee-brown ( and that MUST be done as a "Plug-Chop" operation---not after turning the engine off) I then add about 2% more to the main jet, as a safety buffer if you like. PATIENCE-----PERSEVERANCE-----

On the running issue of my Bullet, think I've reached a fairly happy medium. throttle Needle is now set at it's richest, clip on bottom groove of the five, which made more difference to No. 4 and 3. Still has some low-mid range weak spots, but from there on, half throttle upwards, it goe's like stink. Tops out better than ever with a flickering speedo needle reaching 65-70. Really motors at 55+, feels quite loose and not one hint of a "glitch" noted at these speeds. Checked the plug and it's much healthier with more a darker shade of brown noted with some soot just around the outer part of the plug, the threaded bit. Might of just about got it right at last. Unless you have any more suggestions?

Regards
Bullet Train