Stock carb mod

[Dave31]

I am trying a new approach to the carb dilemma. I am trying out some Butterfly carbs. I will post some of the pic's of them. I still like the KeiHin carb's I have off of some old Yamaha's. But they are expensive and not easy to find. I have been looking for an easy carb to use in place of the Yamaha carb's. So far I like the second one it is the one that is easy to adjust. you can adjust it on the fly. I still need to put a new case gasket in this engine it is still leaking air and messing up the mixture. This is a complete tear down, that is always fun. LOL I will keep you posted on how things go with this one. Have fun, Dave

Very cool Dave, I am very interested on how these work out.

 

[Egor]

I am in Utah now but will be home on Tuesday I will try the Honda carb and see if it is better, I may install another engine to do the tests though this one is getting bad. I am kinda put off with the last pare of engines I got from Dax, I have had good luck with his other engines so I just assumed this would be the same, (not). My best engine came from him. It would be interesting to find out if he is still using the same supplier. There is a chance that the company has just made changes to their motors to make a better profit. These don't have the top of the cylinder milled, they just leave it the way it comes out of the casting, and then just run on a flat sander. The gaskets are the worst I have seen, they just turn to mush. There are not too many suppliers that will send to Cal. Have fun, Dave

 

[ken murphy]

Re:modified----carb app.

I'm so glad were on the same page,just last night the little girl took off w/a 4stroke khin carb
I fab'd a new manifold when the sun cums up i'll take pictures,yes it is nice to feel her take off.
although we put gps on the blue one. (the diamond back I have) top speed flat out 36mph,respectable the the stock sproket,I have a few new things I'll take pictures of,like the
instructions say,the back tire & the motor mouting thats the ticket(but for us the lil girl has to
breathe)be lieve me she's beathen heathen now. I have a couple new mounts I'm workin on to
help w/the vibration

 

[rkorson4209]

I'm fairly new so could someone teach me this, I can't notice anything from the pics

 

[DanielMaia]

Hi guys!

I take off a tillotson carb(butterfly) from a chainsaw, and put directly on intake, but with no air filter. I did some runs, but what happens is the motor accelerates well, but when a try to ride and pull of the clutch, the motor have no such of power. And have another problem..after 1 or 2 minutes, the motor simply dies...i have to wait 5 or 7 minutes to try again, but this last problem i believe that is the own carb with a certain problem that i didn't figured out :S

 

[Egor]

Daniel - You should be able to use that carb, but you need to change settings from the chain saw. I would need to see the carb to be able to tell if it is one that you can change easy. A chain saw is set rich for wide open throttle, that keeps it cool and keeps it going for a long time. You will need to lean it out for the Happy time engine. Have fun, Dave

 

[DanielMaia]

Thanks for the reply dave

Here are the photos as you asked:

Is from a partner chainsaw

I have a walbro from another chainsaw, but i cannot put in the intake, the holes are shorter

 

[Egor]

You should be able to use that. Start with the two screws the have the springs under them, those are the jet adjusters. run them in till they seat, (not too hard) just till they seat. then turn them out 1 1/4 turns. Start with that. The one that looks larger is the main jet, that will be for wide open throttle. The one near the throttle butterfly is the slow jet that is for the idle. You can set that a little closer to the mixture by moving it in and out just a 1/4 turn with the engine running at idle. For the high speed jet make a fast run and then determine if it needs messing with. If it blubbers move it in a 1/4 turn and then try again. Or if it acts like it is starving move it out the same. keep going till it runs just perfect. Have fun, Dave

 

[DanielMaia]

Yes, that's it.

This carb works perfectly in a partner chainsaw, so i can believe that this carb is perfect.

But as i said, the High screw, i turned out 1 1/4 turns. the idle was just 1/4 left. The fact that in idle (with clutch ON) the motor acelerates well, and have a relatevely a good response, but when im going to take a ride, when i took the clutch off, the motor simply start to fail, no torque at all. And im going to test again, but i can run the motor by 30 ou 40sec, then the motor simply dies, and i only can run it again past 1 or 2 minutes.

Sorry for my english

[EDIT] One thing that i have to refer..this type of carb it "sucks" the gasoline with a type of "pump" in the membrane. I put the fuel line, directly in the carb, and i saw that past 20 or 30 sec with the fuel valve ON, the carb droped (weeped) the fuel...

 

[Egor]

Daniel - That carb is a pumper carb and may need the hole to the crankcase. If you look at the chainsaw, in the place the carb goes, see if it has a small hole next to the intake runner. That is to operate the pump. You may be able to make a slot in the gasket over to the main intake runner and get enough of a pulse to make the pump work. Have fun, Dave

Yes, that's it.

This carb works perfectly in a partner chainsaw, so i can believe that this carb is perfect.

But as i said, the High screw, i turned out 1 1/4 turns. the idle was just 1/4 left. The fact that in idle (with clutch ON) the motor acelerates well, and have a relatevely a good response, but when im going to take a ride, when i took the clutch off, the motor simply start to fail, no torque at all. And im going to test again, but i can run the motor by 30 ou 40sec, then the motor simply dies, and i only can run it again past 1 or 2 minutes.

Sorry for my english

[EDIT] One thing that i have to refer..this type of carb it "sucks" the gasoline with a type of "pump" in the membrane. I put the fuel line, directly in the carb, and i saw that past 20 or 30 sec with the fuel valve ON, the carb droped (weeped) the fuel...

 

[DanielMaia]

Exactly egor, i saw that little hole and you took my doubts

I didn't get very well..when you say "You may be able to make a slot in the gasket over to the main intake runner"

 

[ken murphy]

Hey egor my blue bike took 3rd in the spookytooth Holloween race heres the picture from my yellow one and some race pics.
Happy trails
Ken

 

[karma1968]

Re: can you guys seee this?

this is what I did with mine
I smoothed out the entry & actually honed the bore as large as I could without interfeering with the sides of the slide
it definatly helped
take care
JAK

i stripped my carb down today and bore it out and polished. lol it does work...
before the work the motor would bog when warming up. now even cold theirs more power weird..

when i get the chance i wanna drill the hole for the idle but at the moment im happy with it.

 

[DanielMaia]

Re: can you guys seee this?

Very cool karma!

What's the diameter of stock main jet of carb? #70?

thanks

 

[karma1968]

no idea next time i have it apart ill have a look. that would have been the next thing to play with if this mod didn't work..

its a virgin and new so #70 it likely is..

one thing i do need is a gas filter i found some grit on the bottom of the bowl....

 

[DanielMaia]

Heys guys, i just finished modding my carb, and i make an additional mod, take a look:

The bigger is from a kreidler florett rs carb, a bing 21mm i think:

The mod i make:

Lapping the side of intake, dont know if it works, but the other bing slide have it, so i think that will be better

Opinions?

 

[karma1968]

interesting i would guess the idol will be higher. worth testing

 

[Egor]

Daniel - The cut in the slide is for running just off idle, the larger the cut the leaner the mix, if the engine blubbers at that throttle position it needs a larger cut. The number you see on the slide to the Bing carb lets you know what number the cut is. If you start cutting the slide it gets kinda complex, I have done two of the happy engines so far. They were the only ones that needed it. Nice to see someone willing to try some new idea's. These carbs are cheep and if you mess it up they are easy to replace. I did the hole in one for a friend today and got it a little far up the runner, I will see how it turns out, but it will not need the notch in the slide as it is out in the clear. Have fun, Dave

PS: We should be running the needle clip in the middle slot, but all need to be at the top so that indicates the needle is too narrow. The float makes a big difference also.

 

[Egor]

Ken - I would love to make it out for one of those Spooky rides, looks like you all had a blast. How is that Giant carb doing on that happy engine? I have a few to some old Honda 90's out in the garage, and bigger, I could give it a go and see how they would work. Have fun, Dave

 

[Egor]

Well I finished another hopped up build today. Did all the porting and milled the head, and lastly the carb mod. On this carb I got the hole on quite a steep angle so it came out in front of the slide. I was not happy with the way it came out, but I am happy with the way it runs. I let the bike idle for a few minutes and it just clicks along as happy as I am. But the best part is that it is not sloppy at all when you give er the gas it just blips right up there. I am adding the cotton to all of them now. I think this is the first engine I have milled the head ( I am not fond of Detonating ) and these engine are millions of miles away from having the correct amount of engine cooling fins. High comp makes heat and heat makes them ping. We will see so far this bike really moves. I will have to try and keep the customer from spinning this thing apart.

PS: I did not put the notch in the slide on this one.