Hitchcocks Forum

Hi fellow Bullet owners/riders
Has anybody out there in Enfield land fitted a TM28mm flat side Mikuni Carburettor to a 500cc Bullet with an iron barrel?. The engine has been fully tuned with a high compression piston ratio of 9:1 with sports cam’s, open exhaust etc.

If anyone has, could you please supply me with the relevant information? i.e.
• Main jet size
• Pilot jet size
• Needle jet size etc.

I hope anyone out there can help a fellow Enfield enthusiast.

Hi matey !!-------- have you also "tuned" underneath the piston ?? ie}--- main bearings uprated, roller big end, steel con-rod, extra-flow pump etc ??---------if not then it'll all end in tears I'm afraid ....

----------forgot to ask}--Why no Aluminium barrel then ??

IN REPLY TO ALAN R QUESTIO THE ENGINE HAS HAD THE FULL HITCHCOCKS TREATMENT .THE CARB IS THE LAST PIECE OF TUNING WORK TOO BE DONE.

Isn't a 28mm a bit small for a tuned 500? If its a Hitchcocks tuned head the inlet port will have been opened up to take a 32mm or even a 34mm for a top end engine. For the performance you are looking at perhaps consider one of Mr H's Mikuni or Amal kits. Am I correct in assuming its for a racing bike rather then road use?

HI' IAM STAYING WITH A 28MM CARB SO I CAN KEEP THE TEA CADDY AIR BOX'I HAVE FITTED A S/B AIR FILTER INSIDE BOX .IAM MORE INTERESTED IN BOTTOM END THAN TOPEND;TOP SPEED AT PRESENT IS90+ WITH STANDARD CARB JETTED TO SUIT HOPE THIS HELPS.

Hi Jonesy ... as a general thing on the Bullets referred to in this forum I can only say they are all different. In set ups and behavior. I run a mildly tuned 500 cc iron barrel (Mr H tuned cylinder head, free flow exhaust, free flow in take, 8:1 piston). I have used a 30 mm Amal MK2 and the standard 28 mm Mikcarb. The 28 mm is jetted almost to the maximum and it still runs slightly too lean and there's no real gain from the tuned head. The 30 mm shows the potential of the tuned head, but also that a 32 mm might be the right size to really benefit the tuned head. Why go for a 28 mm standard set up Mikcarb when the tuning stage of your bike could benfit the most with a bigger carb? It's not just a question of power, but the engine also runs too hot with the smaller carb. If you visit the Ace Performance Yahoo group you will find much more info on Mikuni flat slide carbs for Bullets. All recommendations points at the 32 mm. But then again it's your bike and it might act totally different from mine... all the best Jacob

One thing to think of, the Mikuni flat slides have the choke/enricher lever on LEFT side, which makes it tedious to operate behind the battery box. Frankly, can be a PITA if you use yours much. Definately go up to the 32mm...28 may be squeezing it a bit. Factory heads are ported enough to support the 32, and you'll never need an upgrade after that.
TS