Topic: Noticed a couple things on my first rides yesterday

[Pielz]

So the bike runs great (k7 750) except one of the pipes is hotter and darkening more than the others. Cylinder 2 specifically. Also it really doesn't want to go over 65. Think that's a main jet thing? Maybe an emulsifier jet isn't clean enough? Really not looking forward to pulling the carbs again. Unless I don't have to.
 
It's been a while since I've dealt with these carbs and was just hoping for a quick spot of advice on where to start tracking that down

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[Pielz]

Btw any of you who helped me with my 530 sprocket conversion, thank you! its made a gigantic difference. So much more peppy for putting around town

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[grcamna2]

Pielz,
Pull all the spark plugs out and put them in order from #1-#4,the plugs will give an indication of how the jetting looks.
Take some close-up pics of them in the sun light,if there is any today.. I lived in PA. for a few yrs.,it was cloudy a lot around Pittsburgh. 

[Pielz]

I'll do that! Should I take it on a ride first or no?

And yeah anymore it seems like it stays overcast constantly!

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[grcamna2]

Does it run on all 4) cylinders now ?
What condition are your points(new?,what brand?)in:timing set ?  Did you also remove your advance mechanism from under the points plate to see if it is within spec ?    

[Pielz]

Points have been swapped for a Dyna III and timing is set properly as far as I can tell. I'll have to check that as well.
 
Yes, all cylinders are firing although the far left was slightly cooler than the others too. But I don't know if that was just a fluke. I'm off work soon, I'll pull the plugs when I get to the garage!

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[grcamna2]

Points have been swapped for a Dyna III and timing is set properly as far as I can tell. I'll have to check that as well.
 
Yes, all cylinders are firing although the far left was slightly cooler than the others too. But I don't know if that was just a fluke. I'm off work soon, I'll pull the plugs when I get to the garage!

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Did you buy that Dyna III new,how's your coil connector wires? Sometimes those bullet connectors can get a little corrosion.I think it would help to double-check all the connections to the Dyna,especially any ground connection to it if applicable.

[ekpent]

 A hotter pipe that is turning blue would indicate a lean condition in my book in that cylinder. As far as not going over 65mph what kind of intake and exhaust pipe are you running and jet sizes and brand if known. Its fun going faster then that.

[Pielz]

Jet sizes are stock according to whatever brand kit 4into1 stocks. I bought the kit that didn't have floats with it. It was about 50 bucks. Exhaust is a delkevic 4into1 that says rejetting isn't necessary so I guess I just took them on their word. I'm about to pull the plugs to check out their color as was asked of me earlier. Just washed the front of the bike so I'm waiting for some water to roll off before pulling the plugs.

Intake is stock

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[Pielz]

Update: I'm a dingus. I have it in my buddy's garage and we don't have a compressor to blow the water out of the plug holes before removing the plugs so I guess I'll be doing this tomorrow haha.

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[Pielz]

Don't wanna get the plugs wet with water if I'm trying to tell if they're wet with gas you know

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[grcamna2]

Don't wanna get the plugs wet with water if I'm trying to tell if they're wet with gas you know

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I need to find a nice little air compressor myself.I had one that operated(homemade)with a small 1 cylinder compressor,small tank and a washing machine motor.I had no problems with that unit for years,it was all on a small base plate.
Pielz,Your carbs are the stock Keihin PD set for the 77-78' ?

[Pielz]

Haha! That's incredibly cool. I've always thought it'd be cool to repurpose an old airplane compressor from WW2 or something to use in the shop. It'd definitely be a cool conversation piece.
 
And yes, they are the PD42s!

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[seanbarney41]

Uneven pipe temperatures and low power tell us you are likely not running on all 4.  Before you pull the plugs, run it for a minute or 2.  Spray water on each pipe and note which pipe doesn't instantly vaporize the water...thats the cylinder/s that are not firing.  Also, that will get rid of the water so you can pull the plugs.

[grcamna2]

Haha! That's incredibly cool. I've always thought it'd be cool to repurpose an old airplane compressor from WW2 or something to use in the shop. It'd definitely be a cool conversation piece.
 
And yes, they are the PD42s!

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I imagine you already know this,but the accelerator pump/s on that rack of carbs is problematic.I think the best way to clean those carbs is full disassembly and lot's of ultrasonic cleaner time:that's a lot of labor  OR lot's of time and TLC.
I have used up a large can of Gumout in a short time cleaning-out that accelerator system(you must be able to tell,I don't like those carbs;I would rather swap them for the K6 or older 'roundtops' which are better imo..),but when the accel. systems are fully clear with every tube squirting the right way from the back of the carbs., then they are somewhat acceptable... lol 

[Pielz]

I'll do that soon here. Hopefully tomorrow afternoon and report back.
 
Last I checked the accelerator pump circuit was spraying from each port properly. It is absolutely a pain though. I didn't remove any part of it but like you said, definitely emptied about a whole can of gumout carb cleaner making sure those passages were clear! If a set were available to me that were better or equal to my current ones in terms of condition, I'd totally convert to an earlier set of carbs.
 
Would it be prudent to just pick up a new set of plugs before any more testing?
 
Btw that leads me to another question, with the Dyna III (which no I didn't buy new but the coils tested well within specs) what sort of plugs would you recommend? I remember the stock ones didn't have the nipple style top to work with my boots. The boots have no resistance. I have resistor plugs in it now

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[grcamna2]

I'll do that soon here. Hopefully tomorrow afternoon and report back.
 
Last I checked the accelerator pump circuit was spraying from each port properly. It is absolutely a pain though. I didn't remove any part of it but like you said, definitely emptied about a whole can of gumout carb cleaner making sure those passages were clear! If a set were available to me that were better or equal to my current ones in terms of condition, I'd totally convert to an earlier set of carbs.
 
Would it be prudent to just pick up a new set of plugs before any more testing?
 
Btw that leads me to another question, with the Dyna III (which no I didn't buy new but the coils tested well within specs) what sort of plugs would you recommend? I remember the stock ones didn't have the nipple style top to work with my boots. The boots have no resistance. I have resistor plugs in it now

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That's the thing with the PD style Keihin K7-K8 carbs,it's SO Easy for just a speck of dirt to find it's way into the accel. pump squirter jets and to lean-out an individual carb:a spotlessly clean fuel tank and a petcock with a sediment bowl will kep those small orfices clean.. I just love the earlier Round-top carbs,So much easier to set-up and keep in tune.When they do need cleaning or jetting,it's a snap !
I hope a fellow sohc4 member here might have a set for sale for a deal for you. 

Your ignition can be tested with an inductive timing light: hook it up to one spark plug wire at a time and see how steady of a spark you get with the strobe.
What is your complete ignition system(origin of where you bought the parts might help but not necess.)including the coils and spark plug wires:any pics ? I hope you used copper core ign. wires.
A new set of plugs can wait,pull the old ones out first to view them inline.

[Pielz]

The passages are so small in that accelerator pump! No clue why that's the best they came up with in terms of maintenance but who knows.. I'm not an engineer and they're a heck of a lot smarter than I'll ever be lol. Hindsight is 2020 and all that.
 
I bought my ignition system 2nd hand from a guy about an hour's drive over from me. A place called heiples cycles that has a huuuge selection of scrap parts off of a ton of older bikes. He happened to have a set that he sold me for about the cost of just the coils. I don't have any photos of the system but I'll make sure I snap a few when I get around to pulling the plugs. Should have some free time tomorrow. It's the green coils and the older style pcb-looking points plate. Plug wires don't have any visible cracks. They're still pretty rubbery and pliable. They're basically car distributor cap style boots that's why they need the nipple on the spark plug threads.
 
I have an inductive timing light as well, I'll have to dig it out and check that it's advancing properly and spark is steady. Hopefully I didn't burn up the coils while working on wiring and having the ignition switch on! I didn't even think about that until just now.

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[grcamna2]

The passages are so small in that accelerator pump! No clue why that's the best they came up with in terms of maintenance but who knows.. I'm not an engineer and they're a heck of a lot smarter than I'll ever be lol. Hindsight is 2020 and all that.
 
I bought my ignition system 2nd hand from a guy about an hour's drive over from me. A place called heiples cycles that has a huuuge selection of scrap parts off of a ton of older bikes. He happened to have a set that he sold me for about the cost of just the coils. I don't have any photos of the system but I'll make sure I snap a few when I get around to pulling the plugs. Should have some free time tomorrow. It's the green coils and the older style pcb-looking points plate. Plug wires don't have any visible cracks. They're still pretty rubbery and pliable. They're basically car distributor cap style boots that's why they need the nipple on the spark plug threads.
 
I have an inductive timing light as well, I'll have to dig it out and check that it's advancing properly and spark is steady. Hopefully I didn't burn up the coils while working on wiring and having the ignition switch on! I didn't even think about that until just now.

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Ok, that helps to have that history on the parts.
I can just venture a wild guess because I'm not next to your bike looking at it.I have seen those silicone automotive wires that have been modified with a brass end misfire and then outright not fire at all.
I like using the copper core ignition HT leads myself.
I like what Sean said about using a water spray bottle when you start it up and run it,see which header pipes get hot/warm right away.
Pull-out those plugs(pics) and number them corresponding to each # cylinder you remove them from so we can see how each cylinder is firing.

[Pielz]

Gotcha. I'll do that asap. But yeah, id absolutely swap out my plug wires but I gave up searching for the ones I needed as I couldn't seem to find any. I was hoping for just a kit that would have them rather than splicing up my own with some of the diy kits I found on eBay. If you know of suitable plug wires that'd work with my coils id be grateful for the info. I can post pictures of those as well.
 
I'll be sure to do the water thing tomorrow too before I pull the plugs and hopefully we'll see exactly which cylinders are being troublesome

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[grcamna2]

Yeah, a few pics of all your ignition components and coils(if you feel like pulling the tank..)and wires with one of the plug ends removed from a plug:inside the cap.I hope it's sunny tomorrow  There are members here who will know better than I do what the pictures will mean as far as your Dyna parts,etc.

[Pielz]

I'll do that! By the way I certainly appreciate all your help here and with the 125! Got the jug and piston kit yesterday. Hopefully your tensioner gets here soon so I can put that engine back together! Quality looks pretty decent on that cylinder kit actually. I'll make sure I update that other post when I start getting things ready to rebuild.

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[grcamna2]

I'll do that! By the way I certainly appreciate all your help here and with the 125! Got the jug and piston kit yesterday. Hopefully your tensioner gets here soon so I can put that engine back together! Quality looks pretty decent on that cylinder kit actually. I'll make sure I update that other post when I start getting things ready to rebuild.

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With that 125 China kit,be sure to see how the piston fits inside the bore,it may be ok.

[Pielz]

I'll do that! By the way I certainly appreciate all your help here and with the 125! Got the jug and piston kit yesterday. Hopefully your tensioner gets here soon so I can put that engine back together! Quality looks pretty decent on that cylinder kit actually. I'll make sure I update that other post when I start getting things ready to rebuild.

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With that 125 China kit,be sure to see how the piston fits inside the bore,it may be ok.

The tolerances are really tight actually. Crosshatching is nice.

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[grcamna2]

Do you know a Powersports machinist you can trust(Automotive machinists always say "that's too tight"..)to take a look at it? Should be between .0004-.002" which to lot's of machinists is "too tight" A good Powersports machinist can tell just by 'feel'.