Cured the low end stumble finally!

[sparkfly88]

So.... How much are all of these mikuni jets gonna cost me......

[Prisoner6]

Mikunis $

So.... How much are all of these mikuni jets gonna cost me......

Check this place out, Kyle ...

I think some of the members get their Mikunis here ...

http://www.jetsrus.com/a_jet_kit_str...1100F_1979.htm

[natemoen]

So.... How much are all of these mikuni jets gonna cost me......

I went to a local stealership once and needed new pilot jets. Guy went in the back and got the try of knock off jets which were $5.50 each. I told the guy I wanted Mikuni jet and he sort of protested and complained that he would have to order them and it would take awhile. He finally got out his parts catalog and we looked them up. $2.36 each, he chuckled a little and just shut up.

[TomB]

The OE jets are a really good start point for jetting but with old/worn carbs and old/worn engines they can only be a start point.

I use jets from anywhere that sells them the cheapest and drill my own, once you're altering jetting the jet sizes are only a number indicating whether you're going up or down in size.

If you have OE jets and need to go up or down you may want to stick to OE manufacture bigger or smaller, but in the end its all down to doing correct plug chops in ALL rev ranges/ throttle openings.

The 110 size is the actual hole diameter, = 1.10mm

[MarkD]

You must use genuine Mikuni jets, IMHO. I struggled with many revving issues for a month, replaced the junky K&L jets that came with the rebuild kits with genuine Mik's, and have had no problems since.

[Rasputin]

The OE jets are a really good start point for jetting but with old/worn carbs and old/worn engines they can only be a start point.

I use jets from anywhere that sells them the cheapest and drill my own, once you're altering jetting the jet sizes are only a number indicating whether you're going up or down in size.

If you have OE jets and need to go up or down you may want to stick to OE manufacture bigger or smaller, but in the end its all down to doing correct plug chops in ALL rev ranges/ throttle openings.

The 110 size is the actual hole diameter, = 1.10mm

As much as I hate to say there is correct info on the UK site... I will have to confirm what TomB has said. There is no better way than a plug read to see what your engine is seeing.

[motoman]

The OE jets are a really good start point for jetting but with old/worn carbs and old/worn engines they can only be a start point.

I use jets from anywhere that sells them the cheapest and drill my own, once you're altering jetting the jet sizes are only a number indicating whether you're going up or down in size.

If you have OE jets and need to go up or down you may want to stick to OE manufacture bigger or smaller, but in the end its all down to doing correct plug chops in ALL rev ranges/ throttle openings.

The 110 size is the actual hole diameter, = 1.10mm

That sizing contrary to what you stated is actually s predetermined flow RATE.Least that is how Mikunis are done.

[skids]

And of course the flow rate is also related to the air bleed holes on the sides.

[TomB]

That sizing contrary to what you stated is actually s predetermined flow RATE.Least that is how Mikunis are done.

I've read the same thing elsewhere, and know that the old Amal carb jet sizes are definitely flow rate numbered as the numbers don't relate to a measured size, however when measuring my genuine Mikuni jets with a view to drilling them I found they were exactly numbered to the equivalent size.

Though not Mikuni specific THIS website has a chart confirming jet vs drill sizes are direct equivalents.

When doing a lot of tuning work I scrounge old smaller/worn jets that folk would normally throw away, and redrill them, once you have the right size you can buy that set new. I know old racers that drill the jets out big and solder in new brass to drill fresh.

I fully acknowledge that different manufacture jets may give a different flow rate because of different lead in tapers or other differences even with the same size holes. I was merely trying to point out that once you've moved from standard jetting when trying to tune worn/old carbs it doesn't really matter which manufacturers jets you use, its all down to a correct full range of throttle openings plug chops.

All too often I read that someone has taken their bike out for a good run, ridden home, stopped the bike on their driveway and taken the plugs out to read them, all they have done is read the plugs from the last thing that engine did, which usually is tickover before switching off, this is not an indication of the complete throttle range.

On the pilot jets? yes the originals with different side hole configerations will affect tune and I would always try to use OE, but the same applies as above, you can move away from OE if done correctly.

[sparkfly88]

Well, As usual though its only ONE cylinder giving me issues...

So maybe my carbs STILL arnt clean enough, if it was the jets giving me issues, all of them would be acting up not just one..at least thats what I'd think.

Each time this surfaces, I hook the color tune on, find the problem cylinder, adjust, and I'm good for a couple days it seems

[Crusty Snippets]

Jets

I know an old racer that still has jets sitting in his tool box. I keep them there for sentimental reasons and the memories.
We would shut off the engine after a WOT run. No idling, no nothing. Full power, high revs and switch it off. Use a 10 times eye glass and look down the core.
Would also use a set of new plugs for this.
After a while you get used to the different sounds coming from the engine. If it is a two stroke and starts to scream you know it is running lean and may stop very quickly. A four stroke will start running hotter. Too rich and neither will run clean and crisp, and lack power. The sponsored riders usually have better tuners than the rest. Steve Baker on a 250 would gain one bike length on me, down the back straight at Westwood. That is all it took to get in front. He also weighed less than me.
Unkle Crusty

[sparkfly88]

For the last couple weeks....it has been riding WONDERFULLY....

I havent done anything to it yet

I must have another issue somewhere beside the carbs if its intermittent like this...


In the back of my mind I want to replace the coils...........I just havent wanted to swallow that price of the coils yet

[IanDMacDonald]

...........I just havent wanted to swallow that price of the coils yet

Or you can save some money and grab-up some Honda VF coils, or something else.

[sparkfly88]

I looked up the honda coils on ebay....I wouldnt really be saving THAT much money...plus, they are used, and who knows how long they'll last

[motoman]

For the last couple weeks....it has been riding WONDERFULLY....

I havent done anything to it yet

I must have another issue somewhere beside the carbs if its intermittent like this...


In the back of my mind I want to replace the coils...........I just havent wanted to swallow that price of the coils yet

Your carbs are having electrical issues.