Re: Crazy Custom Frame Hobbit

Totally normal JBOT /

It’s probably just your ridiculous intake.

Pooling fuel causes all sorts of running problems..

You always want the shortest intake possible along with a downwards slope the whole way.

Re: Crazy Custom Frame Hobbit

Totally normal JBOT /

Any area fuel can pool, even at the reed block intake connection will cause problems.

I’ve done this and had to modify reed blocks and intakes to shorten/angle them better

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Arrrgh yeah that makes sense. Sadly the angle issue is mostly because of the angle of the engine. I'll have to try to figure out how to handle that.

Re: Crazy Custom Frame Hobbit

Tweaker trash /

> Jay Rivett Wrote:

> -------------------------------------------------------

> Tweaker, you got a big place to ride around.

That’s only 1/4 of it and it’s all grass, my dad likes growing grass.........he’s always adding like 10ft of grass on the woods line 😂

Your gonna wanna gear it with low gearing, the engine fucking screams! (edited)

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Any advice as to how to stop the fuel pooling? I feel like even if I shoot it to the side it will still have the reeds at the lowest point of the fuel system

Re: Crazy Custom Frame Hobbit

Totally normal JBOT /

That’s the trick. You put the cyl straight up which makes it hard.

I’m dealing with this a bit on my solo. The intake is on the bottom!

Like I said, it’s gotta flow downward to dump into the cases. You can put the intakes tube slightly higher where it meets the reed so any fuel will flow into the reed block instead of staying in the tube. If you can get fuel into the block it won’t pool. Shorter intakes don’t pool as bad. On one of my hobbits with a stock block I had to modify my reed block so the fuel couldn’t pool by adding divots to the back of the plate that flowed towards the reeds. Worked well

Re: Crazy Custom Frame Hobbit

Joe Schuitema /

After hearing it run in the video, it sounds like you have the choke on. There's no way the intake is making it run that rich with a 180. Is the throttle slide needle jammed upwards?

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

I'll check all those things - putting the jet back in tonight after changing to a 140, the holder snapped, so maybe it was on its way out (it's been through a couple bikes and a lot of tunes now, so I could have over torqued it at some point).

I'll also check that the slide needle isn't jammed or something, but it seems like it's doing alright at idle, and it's more throttle that's causing issues.

Intake tube should drain into the reeds, BUT, it's draining on the intake side of them, rather than the case side.

Re: Crazy Custom Frame Hobbit

Totally normal JBOT /

You can easily tell if it’s pooling by putting the bike on a steep downward angle. It should rev up once the pool clears but it might die when all that raw fuel gets into the cases too

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Makes sense. Once I fix the carb (sigh) I'm going to

1) check that the float is working correctly and it isn't flooding by filling it disconnected from the intake

2) start the bike and warm it up and see if it runs correctly (maybe this fixed it?)

3) take off the intake (while it's warm) and see if there's fuel pooling - if there is I'm going to drain it and see if it runs well while warm and without pooled fuel

4) check piston direction

Re: Crazy Custom Frame Hobbit

I doubt it’s the intake, I would make sure all the stuff in the carb is working properly. The vm20 has a seal between the atomizer and float bowl that can fail and basically never meter fuel properly. There’s also a chance you over torqued it to the intake, flange mount carbs do funky stuff if they are flexing.

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Checked the seal on the atomizer and that's looking in good condition. I'll check the torque at the flange, but I'm hoping it was either that the jet holder was set to fail and causing issues, or it was with the reeds/gasket or something along those lines. I'll check piston direction while waiting for parts to come in!

Re: Crazy Custom Frame Hobbit

I would also check the reeds aren’t messed up too. I recently was chasing an unknown problem (frayed reeds) for weeks, trying jetting all over the place and finally my fiberglass reeds it gave up.

Re: Crazy Custom Frame Hobbit

Totally normal JBOT /

Why doesn’t anyone believe an extra long intake is the issue like it is?

Re: Crazy Custom Frame Hobbit

Because there is obviously something else wrong here. While not ideal, it should still kinda run. It might be less responsive with a long intake than with the carb butted right up to the reed, but it should do more than barely rev out enough to grab the clutch. I have seen many gila-derbi set ups and hobbits with the MLM noodle intake where the intakes are like 8 inches long and it is fine.

Re: Crazy Custom Frame Hobbit

Totally normal JBOT /

Pooling is death.

You ever made an intake that pooled? It’s the worst

Re: Crazy Custom Frame Hobbit

Tweaker trash /

Anyways once you get to run it should fucking scream! My stock except pipe screamed to like 9,000 rpms until I destroyed the crank

Re: Crazy Custom Frame Hobbit

Does it run/rev without the belt on?

Did you pressure test the engine?

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Leakdown test on the engine had almost zero loss, and taking the belt off made little to no difference.

Reeds themselves were in okay condition, but I'm definitely excited to see how it does once it's all back together.

I'll clear up the variable of the pooling when I start it with the steps I noted above. Also definitely gonna check out the choke system of the carb - though I do notice a difference between choke on and off.

Re: Crazy Custom Frame Hobbit

Tweaker trash /

You know what they say...get them running stock then tune them up

Re: Crazy Custom Frame Hobbit

reynie domingo /

If you have a 180 main it would be running rich, it’s running lean in the video, is your gas cap vented, carb vents plugged? Should of just put a derbi motor in it, same thing

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

@carless, yeah, that woulda been the move. I have a much more mild exhaust to go with that kit soooo could try that guy.

@reydom, agreed about the Derbi. Hind sight is 20:20 and somehow I thought this woulda been easier. Guess there's something to say for being a guinea pig. Preeeeeeeetty damn sure it's not running lean in the video. There's a ton of smoke dumping out and it's sounding rich to me. Also every single other person who has seen it has said it's rich, so you're definitely layin out a hot take here. What makes you say it's lean? (edited)

Re: Crazy Custom Frame Hobbit

reynie domingo /

Cuase that’s what it sounds like, it you put the enrichner on and it gets better it’s a good sign it’s lean, run the bike and hold the throttle at a steady position for a while and look at the plugs. Also check the ignition system, ohm out the high tension coil, you should read in the high thousand ohm range. A bad or weak system won’t burn all the fuel and runs rich and won’t rev high

Re: Crazy Custom Frame Hobbit

Tweaker trash /

This engine configuration really opens the motor! I couldn’t believe how high the engine was reving with a stock cylinder. It sounded kitted! I can only imagine with a kitt and lighten flywheel and everything else..that’s going to be insane dawg! (edited)

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

@reydom that makes sense. I don't know that it sounds better with the choke on, though. I'll definitely test the ignition system

Re: Crazy Custom Frame Hobbit

Did you use an automotive leakdown style tester or did you use a pressure gauge and measure loss of psi over time?

From your wording it sounds like you used a leakdown tester, and that will only tell you if your ring seal is good, it wont however tell you if you have a leaky bottom end.

Also how much loss did you see if you did do a "two stroke" pressure test? I usually go for 5psi @ 5 minutes and it should hold that. If not soapy water the cases and find your leak.

I bring this up because air leaks can give almost untuneable over rich conditions on the lower end that then turn to lean at mid/ wot and makes it impossible to tune. You chase your tail forever.

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Oh dang okay, this is super helpful. How does one do a 2 stroke pressure test? I'll do that next. I'll obviously google it immediately after posting this, but if you have a recommended guide I'd love to follow it

Re: Crazy Custom Frame Hobbit

Oh yeah, if you used and automotive a leak down tester wouldn’t have gotten you results. You need to plug the intake or exhaust and then pump a few psi into the cases from whichever one you didn’t plug. I use expansion plugs from o’reily to plug the exhaust port and then use a bit of radiator hose with a hand pump hooked to it. If it holds it’s all good, if not spray various things with soapy water to see where the leak might be seeping. The ignition side seal is usually the culprit on hobbits, the stock ignition has a little lip on it that I use to press the seal into its home. It’s supposed to sit about 5mm or so into the cases. I think you can just press another one in on top of it if you can’t get the old one out. I would inspect both seals and make sure they’re not rolled. It really seems like a case leak to me too. (edited)

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

OK, I see how to do it. Now to figure out how to plug the exhaust on this thing... A flange won't seal it sadly

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Awesome, freeze plug is a great idea. I'll probably just pump it into the top with the leakdown tester threaded in.

Should the reeds seal the intake or should I add a seal?

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