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Post by lcmarky on Aug 3, 2020 12:05:14 GMT 1
My LC motor is having 400cc liners and a reprofiled head via Norbo. Carburettors are Keihin PWK28, with socks, uprated oil pump by Arrow and Nikkon F2 pipes, Vape power dynamo and Ignitech ignition. As I await the barrels etc to be ready I'm looking at the carb's set up and oil injection points. There are as the pic's show the barbed inlets on the top (12 o'clock) of the outlet which have a 2mm dia bore. I have long and short oil nipples from Norbo that have a 1.6mm dia bore. The OEM carb's have the oil injection is at the bottom of the outlet (6 o'clock) and the hole is 0.75mm. Yamaha have engineered this system I presume to give a high flow of oil into the atomised fuel stream for all revs & I'd like to replicate this in my carb's as best I can. The challenge is finding a suitable position for the oil injection ports. I will have some fittings made up that step the inlet diameter down to a 0.75mm exit and an M5 thread to screw into the carb body (will apply some instant metal or similar on actual assembly to strengthen the join). The orange dots are as good as I think I can achieve and I'm conscious I want the oil inlets to be below the horizontal so there's no 'self purging' due to gravity. Reading Howard's thread there are I see some successful alternatives to what I'm trying to achieve, so anyone that has fitted oil injection to their PWK 28's please shout.. Advise on jets/needles also appreciated although once up and running it'll be put on a rolling road to check the AFR. Here's a few pics:  Carb Manifold Assembly by KTM Marky, on Flickr  Carb Manifold Assy by KTM Marky, on Flickr  Manifold face by KTM Marky, on Flickr |
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Post by lcmarky on Aug 3, 2020 12:06:58 GMT 1
Will also swap over the LHS idle screw..
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Post by JonW on Aug 3, 2020 13:36:49 GMT 1
I put a bunch of info on my site when i did mine in my F1 thread I think.
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Post by jessy03 on Aug 3, 2020 14:29:07 GMT 1
You could fit them in to the manifold,  |
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Post by lcmarky on Aug 3, 2020 14:57:59 GMT 1
I thought about injecting into the manifold. The diameter step changes will reduce the air flow speed and I figured wouldn't be the best place (not that I've any experience here, just thinking aloud!). You've no issues with the oil leaking out when the bike's stood still with a top entry?
 Manifold Internal 2 by KTM Marky, on Flickr  Small Oil Injection Nozzle by KTM Marky, on Flickr |
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Post by lcmarky on Aug 3, 2020 15:03:41 GMT 1
I put a bunch of info on my site when i did mine in my F1 thread I think. Thanks - I'll take a look. |
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Post by jessy03 on Aug 3, 2020 15:10:38 GMT 1
You shouldn’t have an issue with oil dripping out if the pump is working correctly.
I’ve used both of those types with no issues so far that is.
Jess
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Post by tacky1 on Aug 3, 2020 15:32:57 GMT 1
I always fit the injectors on the top of the PWKs, I drill the first hole down the same size as the injector barb internal size, then drill down the second hole the same size and dept as the outside of the injector barb, Then press fit the injector with a tiny dab of epoxy just to be safe.. pics of 2 sets of carbs.   |
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Post by midlifecrisisrd on Aug 3, 2020 15:51:35 GMT 1
Mine are in the top as well with no issues
Steve
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Post by botty on Aug 3, 2020 15:56:48 GMT 1
Did mine same as Tacky’s.
No problems
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Post by lcmarky on Aug 3, 2020 16:17:05 GMT 1
Thanks for the responses..
Tacky - where do the barb's come from?
Cheers. Mark
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Post by stusco on Aug 3, 2020 17:26:32 GMT 1
Allens performance did mine in the top
They also drilled the carb body to move the idle screw ,but they drilled it off centre so the screw wouldn’t lift the slide,so I blanked it and reverted to standard but with idle screws from a motorcross site that you can even adjust with your gloves on
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Post by Tobyjugs on Aug 3, 2020 18:33:18 GMT 1
My oil feeds are also feed into the top via a brass spigot. The carbs came like this when I bought them.
Your set up is similar to one I have.
What's the idea behind opening up your manifold on the reed side?
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Post by tacky1 on Aug 3, 2020 21:03:34 GMT 1
Thanks for the responses.. Tacky - where do the barb's come from? Cheers. Mark
I got a bag of them from Yambits, Ive used these on maybe 8 sets of carbs and no probs with them
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Post by wallcraft on Aug 3, 2020 21:51:06 GMT 1
Allens performance did mine in the top They also drilled the carb body to move the idle screw ,but they drilled it off centre so the screw wouldn’t lift the slide,so I blanked it and reverted to standard but with idle screws from a motorcross site that you can even adjust with your gloves on Interesting, what motorcross site was that, could do with some of them. |
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Post by lcmarky on Aug 3, 2020 22:26:47 GMT 1
Thanks for the responses.. Tacky - where do the barb's come from? Cheers. Mark
I got a bag of them from Yambits, Ive used these on maybe 8 sets of carbs and no probs with them
Thx. What is the diameter of the exit hole please? What’s the consensus on going larger than the OEM carb’s oil entry diameter? |
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Post by lcmarky on Aug 3, 2020 22:27:54 GMT 1
My oil feeds are also feed into the top via a brass spigot. The carbs came like this when I bought them. Your set up is similar to one I have. What's the idea behind opening up your manifold on the reed side? Manifold is from Norbo. It’s a nicely engineered design & I’m liking the integral Air balance Channel. |
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Post by jessy03 on Aug 3, 2020 22:41:08 GMT 1
What’s the consensus on going larger than the OEM carb’s oil entry diameter?[/quote]
I’d stick as close as possible to the original diameter 1mm ish
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Post by tacky1 on Aug 3, 2020 23:04:28 GMT 1
I got a bag of them from Yambits, Ive used these on maybe 8 sets of carbs and no probs with them
Thx. What is the diameter of the exit hole please? What’s the consensus on going larger than the OEM carb’s oil entry diameter? Shit, I cant remember the size, I just grab the same size drill bit and bore through and then counter bore the outside dimension to the dept of the injector. I would keep it the same size as the injector hole, My reasoning is....... The oil will hopefully squirt in more rather than dribble in a bigger hole..
Lol, thats my look at it anyway  |
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Post by JonW on Aug 3, 2020 23:59:59 GMT 1
ISTR it was 1mm standard and 1.2 for something bigger. I asked this question a long time back on here and that info came from Nikfubar (RIP).
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Post by rigga on Aug 4, 2020 5:15:59 GMT 1
On the advice of mutts, I used the top ports as is on mine, as its the pump that determines the oil flow, and the size of the ports make sod all difference (I'm paraphrasing his words here)
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Post by stusco on Aug 4, 2020 7:39:00 GMT 1
Allens performance did mine in the top They also drilled the carb body to move the idle screw ,but they drilled it off centre so the screw wouldn’t lift the slide,so I blanked it and reverted to standard but with idle screws from a motorcross site that you can even adjust with your gloves on Interesting, what motorcross site was that, could do with some of them.  |
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Post by lcmarky on Aug 4, 2020 9:52:20 GMT 1
I think the first time I put the carb down on my workbench I very lightly caught the plastic idle screw and it snapped clean off!
You'll see I have replaced them with Brass ones...
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Post by JonW on Aug 4, 2020 13:39:45 GMT 1
One of the things I like about the PJ version is that the choke is also the idle, twist to set and pull for choke. Much simpler than normal handed carbs tho not always easy to reach the choke, but most twins will start on one choke lol.
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Post by lcmarky on Aug 4, 2020 14:14:07 GMT 1
One of the things I like about the PJ version is that the choke is also the idle, twist to set and pull for choke. Much simpler than normal handed carbs tho not always easy to reach the choke, but most twins will start on one choke lol. I did think a twin choke set up was a bit overkill. Would be nicer if they came as a handed pair, with decent idle screws and only a LHS choke. |
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Post by muttsnuts on Aug 4, 2020 15:52:15 GMT 1
put them in the manifold, its a boat laod easier, saves undoing the oil pipes when rejetting if the carbs are coming off (generally required) and works just as well as the oil is pumped through the nozzle/injector which then drops into the air stream and gets atomised as normal while being drawn into the crank cases and through the transfer ports, default Yamaha is to pump the oil up onto the floor of the carb, not the most ideal place to deliver it
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Post by lcmarky on Aug 4, 2020 17:31:33 GMT 1
put them in the manifold, its a boat laod easier, saves undoing the oil pipes when rejetting if the carbs are coming off (generally required) and works just as well as the oil is pumped through the nozzle/injector which then drops into the air stream and gets atomised as normal while being drawn into the crank cases and through the transfer ports, default Yamaha is to pump the oil up onto the floor of the carb, not the most ideal place to deliver it I am all in favour of ease and that's a good point you make about removing the carbs. Appreciate all the responses folks! |
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Post by cb250g5 on Aug 4, 2020 17:48:21 GMT 1
For what it's worth I converted my PWKs to cable chokes and use a LH switchgear off an early R6, with built in choke lever. My oil inlets are at the top and I have big holes, the pump pushes as much as it wants through the holes. 14 or so years and 30 odd thousand miles, no problems.
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Post by midlifecrisisrd on Aug 4, 2020 17:57:39 GMT 1
On my 31k 385 I also used a cable set up
Think it was from a German 550
If doing it on an LC if you search xj550 left switch on ebay you will see a very familiar switch with a choke lever on it
Certainly on the 31k switchgear there are 2 m5 tapped holes on the bottom for the choke housing to screw onto
I found a nos switch and swapped the guts/wiring
Steve
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Post by midlifecrisisrd on Aug 4, 2020 17:59:38 GMT 1
Here's a pic   |
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