Obr 29.5- 990 or 1170?

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Striikar

Striikar

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I'm looking for a few carbs for my engines.
This is for over 29.5 fm stuffed billet engine.
So ddm has sale on 8/10 -11:
Walbro 1107 bearing mod carbs $54.99 reg 69.99

I had decided on 990 but according to others here, I should be good with either.
The sale makes me think maybe I should get 1- 2 of the 1107 instead. I can save some money which is always a good choice. I'm thinking one day I'll eventually get bigger engines and I'll have carb/s that'll be fine for them.
 
I don't have any experience with a 1107 but have been running the 668 & 990, 668 is a good carb with choke & the 990 is a performance carb with no choke. There is a difference between the 990 & 668 that is why they have different stock H/L settings. The 688 is 1&1/4 on low & 1&1/2 on high. The 990 is 1&1/8 on low & 1&5/8 on high according to
http://www.oneillbrothers.com/blog/breakin/
 
Bill Mossor said:
I don't have any experience with a 1107 but have been running the 668 & 990, 668 is a good carb with choke & the 990 is a performance carb with no choke. There is a difference between the 990 & 668 that is why they have different stock H/L settings. The 688 is 1&1/4 on low & 1&1/2 on high. The 990 is 1&1/8 on low & 1&5/8 on high according to
http://www.oneillbrothers.com/blog/breakin/
Click to expand...

I agree with the settings as laid about below but the difference must be in jetting etc because the bore and venturi etc are identical.
I did find that I had to set the low on the 990 at less than 1 to get it running properly.52743Carb settings.webp
 
1107 has a slightly larger venturi then the 990. However if both are properly tuned I doubt anyone of us would be able to tell the difference between the two. The 990 and 813 are the same save the 813 has a accelerator pump.
 
The only difference between the 990 and 668 that I found is that the 990 can be extremely hard to start with no choke so I went back to a 668.
If there was any difference in performance it was so small I couldn't see it.
I've got the 1107 in the toolbox for the day I get a 32cc.
 
Hmm could be set up. The 990 is specd out as the "performance" version of the 668. I'd have to look up specs to see pop off differences and what not. I do admit I prefer the 1107 over the 990. Just my preference though. If buying a complete zen 32cc the 1107 is the stock carb.
 
on the wt990 if you get the popoff at 13psi and reseat at 10psi they start from cold no problems without having a choke in them. Out of box new they popoff around 28-30 psi!!!!!!. Walbro spring# 98-3247 puts you at the 13pop and 10seat. Use only the walbro brand meter arm gauge to set arm as the cheapo"s are stamped like crap.
 
Last edited:
corn juice said:
on the wt990 if you get the popoff at 13psi and reseat at 10psi they start from cold no problems without having a choke in them. Out of box new they popoff around 28-30 psi!!!!!!. Walbro spring# 98-3247 puts you at the 13pop and 10seat
Click to expand...

They can "pop off" whenever they want LOL!
I ended up using starter fluid to get mine going.
 
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