carburetors

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gunner221

gunner221

Well-Known Member
Messages
173
Location
Northants UK
I currently run a 603/a and have a 668a as a spare, I know there is the 813 and what the difference is, but here's the thing is there any real improvement. Should we all be running the 813 or is the improvement minimal and not worth the expense.

should I switch the 603 for my spare 668 and save for a 813 idon't know and everything i seem to read does not really help.
 
yer i know the 813 has no choke and a fuel pump to squirt a little extra for added boost on take off, but is it really worth it and some report having problems and seeing no real gain with the 813.
 
813s are pretty tedious to get the H jet right, especially on a bigger bore engine. I had one and got the shits with it, ripped it off and threw it in the bushes, too much trouble and it did the opposite to what its supposed to do - massive low end bog. Got a 668 and am sticking to them, it seems people running the stock 23 on a baja get a big difference with the 813, the rest are hit and miss - some people swear by them and some people swear at them :censored: - me I'm the latter, tried it on a 26 and a 30.5 and hated it.
 
I have had a 813 on my 30.5 esp ported and tuned motor and the 813 is now very worn and leaking air, I have a titan with a 29.5 and a stuffed crank and was running a brand new 813 and it went well.
This afternoon I put a new stock Walbro on the Titan and a quick tune and it was going harder and faster than before, so much so it lifted the front wheel up and ballooned all 4 fg monster tires.
Its all a learning curve and these engines don't all behave the same.............
 
wt 813 carbs best suitable for 28,5 cc and up.
i have an O´neills 27,2 Reed kit in my car. have drievn it så far whit the 813 carb but have now switched to a 668 carb.
i have modified the 668 carb. I have removed the entire choke assembly and plugged the holes.
the engine is also equiped whit a tuning pipe From RN tuning
 
today i was out testing with the modified wt668 carb on the engine.

det engine is much more responsiv. it formely eksplodes when i hit the throttel
it runs better with the 668 carb. and it ideling much more stable.
all i all . i would say that the 668 or 771 carbs is much more suited to smaler Zenoah engine than the 813.
 
Crazy Beetle said:
wt 813 carbs best suitable for 28,5 cc and up.
i have an O´neills 27,2 Reed kit in my car. have drievn it så far whit the 813 carb but have now switched to a 668 carb.
i have modified the 668 carb. I have removed the entire choke assembly and plugged the holes.
the engine is also equiped whit a tuning pipe From RN tuning
Click to expand...

sorry mate I have to disagree, the 813's seem to be really effective on a stock 23 engine (on a baja for instance) on the larger capacity engines they are hit and miss and are tedious to tune
 
i have to second Monaro here. the 813s i have dealt with went like POO on anything over the 27.2. i ve seen them on a 28.5 and a few 30.5s and just dog dung. but on my neighbors 26, its a MADCARB.

his brother tried the 813 on his 30.5 and blah, hard idle, hard to tune, wouldnt run right. but put the 644 back on, get it marginally tuned and it was off to the races.

i may try his 813 (as its setting in a box now) on my 27.2 and see how it goes.
 
The WT813 may SEEM TO be effectiv.
every thing will seem effectiv on a stock 23cc.


Gunner221@ give it a try. i know it will work.
you can try the 771 to. but you have to give up the choke.

give us a hint when you have tried and let us know what you experienced
 
Last edited:
im using a 771 only problem ive had is the choke its a female dog to start but when it does start then well its good its on my 29cc ddm head zenoah bottom stuffed crank zero drag seals thin copper gasket was look at getting a 813 but like most people i only use car for bashing so always on and off the throttle so didnt bother plus im well happy with my 771 at the moment when it dies i think im going to replace it with 668 so ive got a choke
 
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