wombat carb specs

[mark heckman]

Can someone please post the stock settings on a 28mm mikuni carb for my wombat that has the enduro/cross kit on it ? When I got the bike many years ago it holed a piston. When I took it apart it had the piston with a single window near the top. I replaced it with a piston with 4 holes in it as per the enduro/cross kit. I haven't ridden it much since then & am trying to find the correct carb specs to make sure it is jetted somewhat close.
Thanks,
Mark

[olddogs]

Check the forum archives. Captain Eddy made some starting point recommendations for jetting specs using the Enduro Cross kit and the 28 mm CW carb. Always start on the rich side. Plugs are cheaper than pistons.

[mark heckman]

yea I have looked into the archives & I did find the specs once, but have failed to find them again. I have found posts about main jets & they are quite confusing. Anywhere from 350 to 130 for the main jet. That's a pretty big spread !!

[racerclam]

A reeded carb will normally require 6 to 10 steps larger main jet and sometimes a richer needle ot a raising of stock needle (dropping clip)

Rich

[matt glascock]

Mark, can you confirm that the cylinder has been ported for reed valve operation? I've seen quite a few bikes that had everything for reed conversion except the port work. I've never quite understood the rationale or benefit of simply slapping a reed cage in the induction tract but there they are.

[Bullfrog]

Mark, carb jetting is "machine specific" - the following items have a significant effect on exactly what jetting is required (and the list is NOT exhaustive):
engine size and state of tune
air cleaner design (very free flow or restrictive)
fuel type and pre-mix ratio
exhaust system design (stock street exhaust or expansion chamber . . . which expansion chamber?)
carb flow straightening vanes installed or not
UFO or not
piston port or reed valve
carb size
etc
etc
etc

See page 63 of the Official Hodaka Workshop Manual for specific procedures for tuning the Mikuni carburetor.

Note: I did a bit of searching and found a thread in 2014 about a reed valved Wombat with 24mm carb . . . but that is pretty much useless for your Combat Wombat reeded cylinder with 28mm carb.
Ed

[dirty_rat]

You could look up the jetting for a 98 Super Rat, as they came with a 28mm carb. The jetting used for them might get you into the ballpark. Just a thought. A second thought, is the carb a flange mount or a spigot mount? The two are different and jetting will be different between them. The jetting for the Super Rat is with a 28mm spigot mounted carb, and the jetting for a non-reeded combat wombat is for a 28mm flange mount carb.

[olddogs]

The post I referred to was from Nov 18th, 2013. A question about a CW Enduro Cross kitted engine with the stock 28mm CW carb was asked. In it, it has reference to a 240 main jet with a 40 pilot as a suggested starting point. A 2.0 Slide is mentioned. Even dated information should be helpful when working with the same parts. Simply add all the variables like wear and tear, or how many previous owners were changing out pieces and it becomes trial and hopefully few errors. I have always found a good sized main jet, and tuning with different tapered needles works for me.

[mark heckman]

The carb is a flange mount & I found the specs for stock jetting. Mine matches stock except stock main is 190 & mine is 180. It also now has the 4 hole piston for the reed valve & a 3 window opening on the intake.I'm cleaning it up & getting ready to sell it. Just ordered new petcocks,fuel filter & fuel lines from Paul for it. When I got it many years ago the petcocks were frozen shut & I broke the ears off both nylon bushing.We used to have a guy around here that had Hodaka parts & he kind of fixed them. Well after sitting in my heated garage for the last 8 years they froze & broke again. This bike is kind of different as it has the 94a exhaust pipe with the combat wombat airbox mounted on the left & not the right side. It had 614 miles on it when I got in & it now has 1182 miles on it. I put 568 miles on it in 25 years.

[Bullfrog]

Are all of those 568 miles with the 190 main? If so, you must have been exceedingly kind to the machine! If you are selling the machine, I'd recommend not worrying about having the jetting close (when it hasn't been close for 25 years???). I'd recommend making sure it is rich. Put a 240 (or bigger) main jet in it and a 40 pilot jet . . . to assure the next owner starts out rich and works down from there. Stock Combat Wombat jetting in a stock Combat Wombat 28mm carb on an enduro cross kit is a recipe for seizure.
Ed

[mark heckman]

Thanks Ed, It does have a 35 pilot jet in it & I have an extra 240 main jet. I will take out the 180 main & try the 240. Yea I never rode it very hard.

[mark heckman]

I was just thinking of something pertaining to my Hodaka. When I holed the 2nd piston I took it to a supposedly Hodaka guru. Maybe he put the 180 main in it & that is why I have a 240 in the tool kit. I do Know that he changed the piston from the one rectangular window to the one with a rectangle & 4 holes in it. I probably haven't ridden it 50 miles since, & that was at least 15 years ago.

[Bullfrog]

. . . or the 180 was in there, and that was a major contributor to holing the piston . . .

[Bullfrog]

. . . though it would be good to remember that a seal could have failed and caused an air leak, which made things reeeaalllly lean - and holed the piston . . . (What's the world coming to? I guess you just can't trust rubber seals for a life time. Um, I've been there, done that.)