How do i make an MB5 start easier

Well i dont know much about kickstarts. I am trying to sell this bike but it is really hard to start when its cold. it seriously takes 20+ kicks. I dont want to just take the whole thing apart and clean it if i dont have to.

any quick tips?

thanks.

Re: How do i make an MB5 start easier

new plug

Re: How do i make an MB5 start easier

really? should i go hotter or colder? or just replace it with the recomended plug?

Re: How do i make an MB5 start easier

hotter for the cold weather

Re: How do i make an MB5 start easier

is the choke intact? does it work and are you using it?

starting requires a very rich air:fuel mixture.. about 3:1 (normal running is near 12:1) Starting requires lots of fuel.

choking cuts off air intake and makes the mixture rich.

And a low float level can make it hard for the idle circuit to feed enough gasoline. Air speed through the carb is very slow when starting (and therefore intake "signal" is weak) so proper float level is critical.

And it won't help if the idle mixture adjustments are way off.

Try a squirt of Starter Fluid. If the bike comes to life instantly, check out the carburetor and adjust where necessary.

Re: How do i make an MB5 start easier

good call. Yeah it uses a mikuni carb which i am not familiar with so i am hesitant to take it apart. The choke works and i use it to start it. It does sound like its running rich on colder days though.

I'll try a new plug first.

Re: How do i make an MB5 start easier

oh also. the bike doesnt idle well so i have the idle screw turned up really high. would that make the bike harder to start?

Re: How do i make an MB5 start easier

yes because it would be trying to start at a higher rpm. when the motor is cold it will take longer to start this way if you dont flood it. when the motor is warm it dont so much matter.

Re: How do i make an MB5 start easier

The fact that the bike doesn't idle well is indicative of a bad running condition. not ideling and hard to start mean theres something wrong with the engine configuration. You aren't going to find some tack-on solution, so you may as well start figuring out what the problems is.

Re: How do i make an MB5 start easier

fuck. im am really just worried im gonna start hacking it and never put it back together. your right though. it cant be much harder than a puch to tweak. I mean that is why i bought it in the first place. i just hope it has nothing to do with the transmission. 5 gears scares me.

Re: How do i make an MB5 start easier

No, it won't have anything to do with the clutch or transmission. Just go and buy a carb rebuild kit for $20 or just make sure your pieces are in good condition and set them to spec(105 main jet, needle in the middle position, etc.) and change the plug back to stock and clean the points and fiddle with the timing and i'm sure i'll perk right up.

If that doesn't work, check the compression and maybe decarbonize the head and piston crown. maybe replace the points and condensor with a new assembly.

Re: How do i make an MB5 start easier

I know a guy who's MB5 can be started with your hand on the kick starter. If yours is taking longer, I'd agree with the other guys here and check the carb. They are very finicky bikes from what I hear.

Re: How do i make an MB5 start easier

Luke Evans /

dont worry about the gearbox, virtuly indistructable on a stock machine, the top end comes away like any other ped, posted is pic of my mbx with out the cylinder head, mine was megger carboned up (see attachment) the gasket on it was a solid steel one so i didnt have to replace it, carb strips are easy, the majority of hondas use interchangeable parts fro example, the carb is the same as on the honda h100, mbx50/80/125 mt50 mtx50/80/125

luke

1142987831_dcp00366.jpg

Re: How do i make an MB5 start easier

The carbs aren't that hard to deal with. Have you cleaned it recently? Any dirt will cause problems.

Re: How do i make an MB5 start easier

Harold, Send that MB5 to me here in Wisconsin. I will gladly fix it for FREE and you can come pick it up after I have sucessfully put on 8,000 plus test miles. Sound good? Seriously, if you have points make sure they are clean and prpoerly gapped. Install a new plug and check that your getting a fat spark when you kick it over. Also make sure that your compression is up to snuff, at least 100 psi. Maybe more just to run? Anyone have a good rule-of-thumb for a 2-stroke compression? Make sure that your carb is clean. Take your carb, diassemble it, and spray carb cleaner in all your jets + air passages to help flush out the crud. A carb kit isn't really necessary unless your carb leaks or burns excessive fuel. It isn't a bad idea either though. Usually just the float needle is bad. When taking a carb apart, note the position of needle clips and mixture screws so reassembly goes smooth.

Re: How do i make an MB5 start easier

Hmmz, MB's don't have points!!! Anyhow, the basic setting for a Mikuni (I presume a 16mm version?) is: turn the airscrew all the way in, and open it up again 2 full rotations. Then adjust the idle screw to your need. Cold starting always needs to be done with the choke on, so don't forget that the choke sticks on a Mikuni carb. (while it immediatly jumps back once released on the original Keihin carb.)

grz Thijs

Re: How do i make an MB5 start easier

Of course it has CDI, I should have guessed that.

Re: How do i make an MB5 start easier

wait whats the difference between the air screw and the idel screw. all i saw was an idle screw.

Re: How do i make an MB5 start easier

I have never even seen one of these so I had no idea of what type of ignition it had. That was why I suggested to check the spark after putting a new plug in. Sounds to me like low comp, weak spark, and/or dirty carb. All will cause hard starting along with about 10 other things. Keep truckin' away prooving out one thing at a time. When it gets real rough then ask more questions.

Re: How do i make an MB5 start easier

Look better then. The idle screw is the one positioned near the throttle-operator.

grz Thijs

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