Ewadz3006

Hello all. I recently got a hpi Baja 5b. It had been sitting and the fuel lines were shot. Not sure if it would even run, I just replaced the fuel lines. It needs the grommet for the tank too. The bottom of the tank was all nasty. I took tank out and cleaned it, and replaced the lines, and just silicones the grommet for the mean time. I also took the carb off and cleaned it. The fuel bulb was also dry rotted. ( I hate this ethanol fuel) so I got a new bulb.

Here's what's happening, the bulb doesn't quite fill like I think it should. Gas goes in but doesn't fill it. Seems like it has air or something but I don't see any leaks out side the carb/ lines. I did manage to get it running but it doesn't want to idle. I'm not real familiar with this type of carb. When running it doesn't really seem to have a lot of power off the bottom. I'm not sure if it's just cause it's so big. It goes ok I guess. I've never seen one of these run so I don't know what to expect.

Also I've read pipes make a huge difference in these. Is there any 1 pipe that's better, or one that is all around good. Without spending a fortune?

Also I've seen a couple places talk about a Chinese clone? How do I know if I have one?



Tldr..
1is there a troubleshooting guide for these carbs?
2 what pipes/ mods are good on this car?
3how do I know I don't have a Chinese clone?

sheograth

Are you still using Ethanol mix? If that's the case it might be part or all of your problem. As far as pipes go. I'd recommend the DDM Dominator pipe. It's powerful without being too large or expensive.

Ewadz3006

the gas thats in it is regular gas with star tron treatment in it. its just 87 octane. do these need higher octane?

Ewadz3006

I got the purge ( primer) working like it should. It idles fine now but I couldn't get it dialed in perfect. Does anybody know what the factory settings are on this carb? Its a walbro 668. The low speed needle was at 1 turn out and the high speed was at 1-1/4 out. Both needed to come out a tax to make it run better.

cbaker65

If your fuel lines & primer bulb was rotten ,I'm surprised that the carb hasn't dried up !
The carbs have a diaphragm pump in them that operates a fuel needle ,they dry up an
hardens up.
My suggestion is to kit the carb an replace the diaphrams!...

Ewadz3006

Im getting all new gaskets and diaphragm. primer bulb was rotten btw. its sucking air i think. ill report back later after i replace everything.

cbaker65

Cool!
I repair a lot of weedeaters & blowers ,I buy my kits from ebay ,you just need to know the # of the carb.
Some times I get the diaphrams out an visually match them up with the pics of the kits that the seller shows
of the kit.
The carb also has a diaphragm that consist of little flappers on them that allow fuel flow in the carb ports.
Sometimes you can get by by just replacing the main fuel pump diaphragm ,but more than likely ,those
little flappers are getting hard as well.
All those diaphrams are suppose to be soft an limber!..

Ewadz3006

Thanks cbaker! I actually went to a local stihl dealer that also services small engines. I bought a carb rebuild kit and new fuel lines and new fuel filter and spark plug. He brought out a couple different kits and they all had the same diaphragm and "reed" gasket. ( I think that's what it's called). Got it together it runs good now.

It may need a little more fine tuning but it's close. I must say, if I spent the 1100$ retail on this thing I would be more than upset. The performance isn't anything close to what I thought it might be.

cbaker65

That's great ,those engine shops come in handy for parts on these.
There's basicly only 2 brands of carbs ,walbro or zama,but over the years they made so many different carbs.
Usually the fuel pump diaphragm had remained the same but that reed with the flappers had been changed around
for some stupid reason.
The smog regulations henders a lot of manufactures on these small engines ,especially here in California.
The carbs that they put on the new weedeaters an leaf blowers are junk,Ive had to replace a bunch of carbs,
as a kit would not fix them.
A whole new carb for the new echo weedeaters are only 15 buck now to buy!....LOL

You can only tune the needles so much until the power starts to drop back off.

The low needle is the transition from idle to full throttle.
Adjust that until you have a quick smooth throttle response from idle to full throttle with out
bogging or lag.

High needle is set while running at full throttle until you can here that high end power band.Anymore turns after that ,the power
will drop off!

These sets are best done while engine is running an the buggy setting on a block!

mazpr

I always run 93 with full or semi synthetic valvoline oil (2 stroke dirt bikes).

Just buy a new carb, throw away that one.

Ewadz3006

With the carb kit it runs great just not the power I had hoped for. Starts right up, 2 pulls after sitting for however long. Idles fine. As far as gas I just try to use ethanol free, or treat it with star Tron. On this I used Stihl ultra oil.

On my boat I ended up just getting a new carb. I got a rebuild kit but it wasn't exactly the same. And didn't seem right. I threw in the towel and got a new carb. It runs like a top now too.