TOPIC:

Tyrell Corp wrote: The 115 jets sound a bit small, I'm running 137.5 on mine, another member here recently went to a similar big size. with a 4-1 on pods. It sounds too big I know, but feed the cat.

At 6k this is when main It had 110s before and now it seems worse. I've had this problem to a small, intermittent degree, since I've had it running. Even with the original leaky headers and mufflers. I'm sure altitude is a factor the ride yesterday ranged from 4000-5000 ft without going up the canyons, too cold and risky running across an ice patch. I'll raise the needles and see if it gets better or worse. Then look into up-sizing the jets if prudent.
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What should the stock jet sizes be? With the altitude here in Utah, the stock settings would most likely be verging on too rich already, other than a lot of early 80's bikes were jetted so lean for emissions legislation. I don't know if you've ever had them set to stock settings, but I'd go back to those if you can, see where you are at and then work from there changing one thing at a time. I have a V&H on my KZ650 otherwise it's pretty much stock and it runs perfectly on the stock jet sizes here in UT at altitude. It looks from the pictures that you are still running the stock airbox, so you shouldn't need huge changes just for an exhaust and like I said the altitude might be enough to already compensate for that. What do your plugs look like are you sure the bogging at high rpm is not too much fuel, try pulling the choke on a little when it's doing it and see if that makes it better or worse, that way you will know if you are too weak or too rich.

swest wrote: Who gives a SHT what others think as long as you like it.
Steve

I know, It is nice to know if it something is way off base. You definitely know what I mean.

I besides the jacked rear blinker mounts I'm leaving everything alone/reversible. I'd like to reuse other bike parts like I've done for the taillight and blinkers ('07 ZR7) and headlight ('82 Spectre}. I'm trying to keep the aftermarket parts to a minimum, at least use used parts like the fender delete kit. Even then i made use aof the left over 20 gauge SS sheet to make the mounts for my green coils.





This just before I tucked up everything ran a wire from 2-3 trigger contact to the tach wire and put everything back.

redhawk4 wrote:
What should the stock jet sizes be? With the altitude here in Utah, the stock settings would most likely be verging on too rich already, other than a lot of early 80's bikes were jetted so lean for emissions legislation. I don't know if you've ever had them set to stock settings, but I'd go back to those if you can, see where you are at and then work from there changing one thing at a time. I have a V&H on my KZ650 otherwise it's pretty much stock and it runs perfectly on the stock jet sizes here in UT at altitude. It looks from the pictures that you are still running the stock airbox, so you shouldn't need huge changes just for an exhaust and like I said the altitude might be enough to already compensate for that. What do your plugs look like are you sure the bogging at high rpm is not too much fuel, try pulling the choke on a little when it's doing it and see if that makes it better or worse, that way you will know if you are too weak or too rich.

That what I was thinking. The stock size is 110 which is what was in there. I wasn't sure how much the pipes and muffler would affect the mixture so I took a blind stab and up jetted. The rebuild kits came with 2 sets of jets 110 and 115 so I swapped them over. I didn't think to open the enriching circuit until I got home. it was so cold I didn't want to go back out. I'll play with the needles a bit, up and down, and see what happens next time it warms up some.

Redhawk, the (avatar) bike is running on pods and a 4-1, it runs really nice from off idle past the redline, plugs look ok and fuel consumption about what I expect 45 mpg maybe. It has an 'air corrector kit' and the needles are different too. I bought the bike like that and it runs so nice I haven't changed anything. ( I suspectthe PO may have had quite a bit of trial and error to get there.

The conventional wisdom of going up two main jets sizes as a starting point seems way off on these, a couple of other 750R owners here are using similar sizes. A carb specialist recommended going even bigger. Odd I know, a couple of sizes up usually works for the 550's...but it works really nice.

Ok

I just decided to jump on the bike and see if playing with the choke made any difference. I grabbed my heavy gloves and helmet and my cyborg balaclava. besides that i had a fairly heavy letterman's type jacket with my company's logo on it.

So I pulled it out to let it warm up while i got my helmet and gloves and my Left side cover was missing. it must have fallen off yesterday during the ride and I didn't notice. I know I put it back on and it was nowhere in the garage. I was just freezing when i got back and pulled it in without really looking the bike over. This is just great! Nick, you wouldn't happen to have one would you?

Anyway, I ran it around the approx 12 mile route, about a 3rd of it freeway. I played with the choke throttle and gear/speed position and I'm not sure if i got it running any better with the choke or not, Maybe a slightly better. The exhaust was popping a bit when I was off the throttle especially towards the end of the ride, That's a lean condition indicator right? I didn't pull the plugs cause I'm still thawing out. It wasn't acting this way before i swapped the jets and you'd think it wouldn't be something I'd encounter since I supposedly made the mixture richer. Maybe this bike is just too cold blooded to run in this cold weather.

Sorry to hear you lost your sidepanel...something about Left hand panels, much, much rarer than rights. The GPz750 side panel embem is very difficult to find now, I had to get one from USA.

Mine pops through the pipe on the overun, I like it. This is a closed throttle condition, you can tweak the pilot airscrews if you want to tune it out but it isn't too much related to your mainjet selection. Have you had it pulling cleanly to the redline before? (these are fast bikes, it is wise to build it up slowly as you get more accustomed to it)

Sorry, don't have a side panel, that sucks, remember losing one of my 1000J shortly after I bought it, that was annoying,but in 1982 you could just go to the dealer and order a new one painted and with emblems for 30 English pounds, seems like a bargain now, at the time it was probably close to 10% of my take home pay

If it were me I would put everything back to the stock settings and work back from there. If we're not careful by the time we've messed with a few things, jets, needle settings etc. we have no idea where we are and also if there's some other underlying problem. IMO the bike should run somewhere near at 4500 feet with the stock setup and a 4-1. It may be a little weak, but not so bad that you would experience major performance issues. If it's still performing badly then the issue likely lies elsewhere in the fueling, as opposed to being an adjustment or jet change. Is the ignition performing as it should?.

I know people are using big jets with Pods, but those are effecting the vacuum characteristics and so forth, so is not a direct comparison to your situation and also they are not at altitude. I've seen the jet sizes some run in XR650L bikes like mine and wonder how, because at 5000 feet where I am, if I go more than one size over stock on the pilot jet it really bogs on acceleration.

Stock bikes ran very well out of the box, just a 4-1 would not mess that up too much, it likely would produce a lean condition that you wouldn't want to run with long term, but the bike should still run well, particularly at altitude, since you could already be one size higher than necessary just by running stock settings in Utah on a stock bike.

Popping if directly carb related, as opposed to air leaks, exhaust leaks and unburnt fuel in the exhaust is going to be a pilot jet issue, not main jets as the throttle is closed on the over run. If the mixture at that point is very lean then it will pop.

My bike turns into a dog at 4500'.
Steve

swest wrote: My bike turns into a dog at 4500'.
Steve

Will it fetch a stick if you throw it Must be really scary when it takes off after a cat Must terrify the Mailman too

That's an example of what I'm talking about, if you lived here you'd be jetting it down, "it turns into a dog" because it's too rich and will begin to bog on the pilot jet size most likely , the main jet size is more forgiving because you are at higher rpm, where it tends to keep itself clear even if it's a bit rich.

I'm really pissed about the side cover. It was in excellent shape even if Iwere able to find it along my route it wouldn't be in very good shape any more. i have only found one so far and it's in Canada the A- hole wants $60 for it plus shipping and it's cracked! I'll start looking for KZ750L3, Z750P and KZ700A panels.

The ironic thing about it is that i wasn't planning on keeping the GPz panels on it anyway. I have a set of '82 KZ750E2 panels that I was going to use once I was at a point of finishing it to give a little more classic look. I still wanted to hang on to the originals just in case I do end up bringing it back to stock.

It will run up through redline in all gears except in 5th at full speed it will go up to 7-8k seemingly through momentum then just drop to 6 then not go any higher unless i down shift and coax it up but then it's still a struggle. I think maybe I'll put the 110s back in and raise the needles to see how that works.

It was popping just after I putt the header on and before I repacked the muffler. I opened up the pilots 1/2 a turn and it went away.

BTW iPads suck. I started to reply to posts last night like 3 or 4 times and it kept getting messed up so I gave up and went to bed.

I lost a side cover 20 years ago, turned around and watched as some a$$hole drove over it on purpose. I got a aftermarket one then a known thief stole the other one as I was waiting for my son at Mother's pizza after a extra class he had to take to graduate HS. He ditched those classes and didn't pass by 7 credits. Not only do I have cheesy side covers, the kid wanted me to help him go back to school. "You're 18, get a job and get yourself through school." I told him.
These covers screw on and I haven't lost one since. Every time I look at them I'm reminded of that time.
My new HP bike lap top is a PITA too. It jumps around, switches pages, they are constantly trying to sell me more things like memory, Apps etc. and upgrade to Windows 10 for free. This thing is about to learn how to fly. I miss my old 98 machine.
Oh and my KZ 1000 ST side covers.
Steve

If worst comes to worst I have two left covers, they both looks like #@$^ and I just droped them of at my buddy that is going to paint my R1 this winter. They both have cracks around the lower fastner, I gave him two kits of side covers and asked him to do what he could. I can ask him to try to salvage both. But it will in that case not be firecracker red.
I will keep you posted if he is able to get both fixed.
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