Keihin MK1

Can someone direct me to a parts diagram for a MK1, or explain what exactly is the difference between the MK1 and the more modern versions? I've tried google, but nothing worhtwhile came up.
I'm especially interested if there are any jets missing or extra in this carb compared to the more modern ones? I'm trying to get my head around how these carbs work, but it's difficult since, most the online stuff I have found is for the MK2 carb wich apparantly has more jets in it?

Anyone else have an MK1 carb on their husa? I've had some problems fitting it, the bottom cable touched the valve cover, so I had to grind of the rivets holding the throttle cable bracket and reposition it all the way up, now i've got about 8mm clearance. (old position is still visible on the bracket)

And the stock cables I ordered for a +04 husa were slightly too long, I solved this by welding two nuts onto the throttle cable brackets giving me the length I needed. does it matter in wich hole on the throttle shaft the cables are?

BB

wqell it seems to me that the doc is riddled with mark 1 over mark 2 stuff. because most of us bought ours off a breaker the bikes they came from were old so in many cases the carbs are 7/8 years old now.

the later carb is more tilted compared to the venturi that runs through it. it also has a very technical way of using the squirt but if you do the Taff mod you have 90% of it. the mark 2 can bleed off extra pressure which allows short opening times.

the mark 2 can't change the MAJ but as i'm the only person i ever heard of that played with this jet then it won't be a great loss!

the later carb has a different PJ with aeration ports in the jet.

i'm struggling to think what else but to be fair i've never run one - i've just modified them!

regards

Taffy

I'm having difficulties understanding the doc, lot of 'slang' and abbreviations in there wich make it difficult for me to understand (could also be that my IQ of 49 has something to do with it )

You say in one of the many jetting threads you have answered that there is a method for changing the AP squirt in the doc, but I can't find.

DaleO (many thanks!) gave me this link to the 'BK mod' wich is exactly the kind of info I needed for the MK1 carb. http://www.4strokes.com/tech/ktm/jetmods.asp

Another thing you mentioned in one of the many jetting threads is the starter jet. Does a MK1 carb have this jet?

ya daft twit!

the Taff mod is for the MK1 and the BK mod is for the MK2.

i'll go back and check the taff mod info now. i don't think he knew a thing he was on about!

i gave you the differences in the carbs - unimpressed or confused?

regards

Taffy

Taffy said:

ya daft twit!

the Taff mod is for the MK1 and the BK mod is for the MK2.

i'll go back and check the taff mod info now. i don't think he knew a thing he was on about!

i gave you the differences in the carbs - unimpressed or confused?

regards

Taffy

Click to expand...

I've just reread teh carburation page ( again ) and cannot find the taff mod you speak about

Re: RE: Keihin MK1

Taffy said:

BB



the later carb is more tilted compared to the venturi that runs through it. it also has a very technical way of using the squirt but if you do the Taff mod you have 90% of it. the mark 2 can bleed off extra pressure which allows short opening times.



regards

Taffy

Click to expand...

the difference in tilt would explain the poor fit on the 650 then.

That would be the leak jet then? That bleeds of the extra pressure? And my mk1 hasn't got one?

RE: Re: RE: Keihin MK1

correct - no leak jet. isn't really necessary.

i have now put up the taff mod and BK mod in the doc under carburation.

go look at motoman393 for an excellent description!

regards

Taffy

Re: RE: Re: RE: Keihin MK1

Taffy said:

correct - no leak jet. isn't really necessary.

i have now put up the taff mod and BK mod in the doc under carburation.

go look at motoman393 for an excellent description!

regards

Taffy

Click to expand...

Sorry to keep bothering you but has the MK1 a starter jet? or is this jet part of the choke system on the later carbs?

RE: Re: RE: Re: RE: Keihin MK1

if you buy a sudco carb or allens they have no sstarter jet. all other OEM carbs have a starter jet. the starter jet is the choke jet.

regards

Taffy

For what its worth, my understanding of the terminology is that originally carbs had chokes for cold starting, normally between the carb and the filter. This was typically a butterfly valve, although sometimes a slide, a bit like another throttle plate on the other side of the carb that when activated results in an increase in vacuum over the jets which sucks in extra fuel for cold starts, it choked off the air supply, hence the term choke.

As carbs evolved, the choke was identified as an airflow restriction and to improve performance was removed. The cold starting enrichment now provided by an extra fuel circuit, originally known as a cold start enrichener that includes a valve and a jet to regulate the fuel supply. This now often gets called a choke jet, which is really nothing to do with being a choke. They are also called a start jet, and a cold start enrichener. There may be other terms used too, but they are all mean the same thing, unless you actually have a choke.

As Taffy says, and as far as I can tell the Mk1 and Mk2 are fundamentally the same. They differ a bit in the detail of how the AP (Accelerator Pump) works and not much else. There are some pics in my gallery of a MK1 on my 501 and an AP mod on my 650 MK2.

FCR Keihins are good things on Bergs!

http://www.husaberg.org/index.php?set_a ... _photo.php
http://www.husaberg.org/index.php?set_a ... php&page=5

Cheers
Steve

Re: RE: Re: RE: Re: RE: Keihin MK1

Taffy said:

if you buy a sudco carb or allens they have no sstarter jet. all other OEM carbs have a starter jet. the starter jet is the choke jet.

regards

Taffy

Click to expand...

Mine has no choke, hotstart or tps, so it's probably on of these then. I'll take some pictures to make sure.

thanks yet again for the reply!

steve said:

As Taffy says, and as far as I can tell the Mk1 and Mk2 are fundamentally the same. They differ a bit in the detail of how the AP (Accelerator Pump) works and not much else. There are some pics in my gallery of a MK1 on my 501 and an AP mod on my 650 MK2.

Click to expand...

Thanks for the explanation on the choke!

I have found that the internals are also a bit different. I'll take some pictures, as they say a picture says more than a thousand words!

in that case BB you need to keep the APJ as big fat and open as you can get and open it the old american way!

regards

Taffy

i,ve been through some of this before,wrong parts being sent to me,only to find out the bike had a mk1 fcr and not a mk2.
i uploaded pics in my gallery of the fcr breakdown if interested.

..weed..

popup said:

i,ve been through some of this before,wrong parts being sent to me,only to find out the bike had a mk1 fcr and not a mk2.
i uploaded pics in my gallery of the fcr breakdown if interested.

..weed..

Click to expand...

Thanks for that!

Taffy said:

in that case BB you need to keep the APJ as big fat and open as you can get and open it the old american way!

regards

Taffy

Click to expand...

I've got the carb pictured in the parts diagram by 'popup', so is that the MK1 or yet another version? Since you stated in one of your previous posts that the MK1 has a choke system wich this carb doesn't have.

So does not having a choke system affect the pilot jet size? I was going to follow you preferred settings and use a 38 PJ? I've got the lineaweaver kit with the adjustable APJ any suggestions on the setting?

One last thing, anyone know of an on line source for Keihin jets. Especially the older style PJ. Keihin.de doesn't offer them, and I've found one UK site that offers them but no smaller than 40.

Thanks.

[email protected]

this is daryll at allins performance. they don't start again until next monday. they have them down to 35.

now then, check again but i didn't say anything about choke = any mopdel. i said that keihin supplied carbs have no choke jet.

you must keep the APJ and probably at full squirt. or maybe try halving it. fact is you'll need to pump the throttle several times to get it ready to start. you missed the 'american' bit.......never mind!

the mk1s have the rod on the side - it's THAT simple. i have now upgraded the APJ mod on the doc so you really need to check it out.

regards

Taffy

For playing with jet sizes you can get some jet drills and number drills, and get a pin vice to hold them too, I have got some from ebay fairly cheaply. You can then solder up the jets with normal lead solder used for electrical work and then drill them out to smaller sizes. A good idea is to use a micrometer to check the drill sizes too, just in case.

As an aside, I've been playing with my wifes KLX 250. I installed a 300 kit in it and a big bore Staintune header, keeping the standard muffler, for her Christmas present. I've got it running well with a 120 main, that happens to be a bored and drilled FCR start jet I had lying around from my Berg experiments that happens to fit nicely into its CV carb main jet holder. 120 is down from the 132 standard for the 250. The kit includes a needle which I believe is a standard KLX 300 needle from other markets which I'm running on the middle clip and a 138 main. So I'm down from a kit supplied 138 to a 120 and by comparison to standard its now a torque monster, she is pulling 1 to 2 gears higher up long hills now, and is finding it easier to ride, which was the objective. An automatic would actually be her ideal, but then we are getting further off topic.

A long winded way of saying that some solder and some drills can be a lot cheaper than buying lots of jets.

Steve

yes but you didn't blow hundreds of dollars so it's no good. i'm sorry!

as they say; "there is no replacement for displacement (from ur wallet)"

LOL!!!!!!!!!

regards

Taffy

Great Tips steve. Makes me happy to know someone else does that too!

if your're too cheap even to buy number drills you can also use spring steel wire of appropriate diameter filed or ground on 4 sides into a tapered reamer. wire is available from music stores and model shops.

End result is that the hole diameter is closer to the round shank diameter of your home made reamer than the hole made with a drill is to the drill shank diameter and results in more consistent hole sizes than you get with drill bits.

Like Steve said Its important to measure the thing making the hole, also worth checking the hole size in numbered jets they are often wrong, the worst I have seen was a jet marked 178 that measured 173. more common is something like a 160 measuring 158.

Hope this helps someone

Bushy