end cans different tempreture after ride. whats the cause?

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graham heise
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end cans different tempreture after ride. whats the cause?

#1 Post by graham heise » Thu Jun 28, 2018 7:06 am

G'day. After every ride i take my gloves of to feel the end cans. I notice my left side can is hotter. i also pull the plugs. Both plugs are a rich brown and look the equal to each other. (stock jets with pipes) Bike runs really well on a fresh engine with all new seals. My question is what isthe cause of left side end can being hotter. i would first think air leakand it's running leaner? but the plugs make me think it maybe something else. Is it possible the left side carb is runninga little bit infront of the right? i have rebalanced the carbs and feel they are now spot on within a poofteenth of each other. whats your thoughts? yer i should do a leak down test to be sure.
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hondaror
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Re: end cans different tempreture after ride. whats the caus

#2 Post by hondaror » Sat Jun 30, 2018 4:29 am

Coolant passes through the right cylinder first, then makes it's way to the left.
Rory
2 1984 RZ350s
1985 RZ350
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evan_calgary
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Re: end cans different tempreture after ride. whats the caus

#3 Post by evan_calgary » Sat Jun 30, 2018 6:33 pm

non-synced carbs can do this while left sitting at idle but it sounds like you have ruled that out.

Bare
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Re: end cans different tempreture after ride. whats the caus

#4 Post by Bare » Mon Jul 02, 2018 11:33 pm

Slightly off set (worn & shifted) Crank 'could' cause a bit different ignition timing point ie; differing heat in each pipe

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wolfman
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Re: end cans different tempreture after ride. whats the caus

#5 Post by wolfman » Tue Jul 03, 2018 1:49 am

Depending on type of pipes and how long the pipes have been in use, the baffles will load up with carbon and need cleaned out.
If you haven’t re-packed your silencers in a while, That could be the cause ?
Can’t ever go wrong with a leak down test :smt023
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MK
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Re: end cans different tempreture after ride. whats the caus

#6 Post by MK » Tue Jul 03, 2018 12:26 pm

Most likely causes:
1) Carb sync
2) Carb sync
And last but not least
3) Carb sync

So how exactly did you "sync" them?

But even that does not mean they run equally on both sides.
Float level, idle adjuster or idle air srew positions can be different. Compression, reeds, air leaks - all cause one side to run richer/leaner than the other.
The side that takes more work usually gets hotter - I'd start searching the colder one.
Bye
Martin

hondaror
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Re: end cans different tempreture after ride. whats the caus

#7 Post by hondaror » Tue Jul 03, 2018 5:31 pm

Could it be carb sync? Lol.

The left carb on the power jet carbs of the F2 has a richer power jet. This is for that difference in temp for the cylinders. An attempt to cool things down a bit.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
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2005 749 with 999 engine

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Re: end cans different tempreture after ride. whats the caus

#8 Post by MK » Wed Jul 04, 2018 5:19 am

Just to give a bit more background:
That kind of temp differences usually are caused by partial load differences in carburetion. Most commonly different height of the slide, but as mentioned before it could be other reasons as well.

Plug color is more or less a WOT indicator and thus not really suited to diagnose "equally" running cylinders.
EGT would do that job perfectly.
If that's not available, a cheap version is an infrared thermometer. Let the bike idle and check pipe wall temp on left/right header.

Another indicator is to "feel the gas pressure" by bare hands at the can ends. If one cylinder runs poor, you really feel less gas coming out from that side.
Bye
Martin

graham heise
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Re: end cans different tempreture after ride. whats the caus

#9 Post by graham heise » Wed Jul 04, 2018 6:17 am

thanks for the replys gents. All good ideas and food for thought. the bike is an lc, the fresh crank was trued before install. both cylinders run bang on 135psi. the carbs are original 4lo with new brass.
The float levels were set and re checked with fluid level from drain tube to outside of bowls.
I have reset the balance a few times using 2/ 8mm drill bits under the slides. then when i run the bike it runs well and smooth. exhuast pressure feels equal when blipping throttle. left can is still hotter. I have even tried some test runs by raising the right slide a half turn and another half turn on right side adjuster. it does balance out the heat in the end cans but it does not run as smooth.
In the past i have fine tuned the carb balance on my rz by fine adjustments on one cable whilst riding, listening and feel of the engine. I find one chamber will rattle (rat a tat tat) before the other when carbs are out. when there in it all blends.
I think next move will be to check the packing in the end cans, also i might swap reed blocks over. they are fitted with tdr fiber reeds but i noticed that the don't quite seal at the ends which is a concern. i do have the stock petals i could try. i also might look at trying a spare throttle cable i have also some 31k carbs i have.
Another thing i have thought of is the seal (or lack of) between carb joint to airbox in the lc.
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Re: end cans different tempreture after ride. whats the caus

#10 Post by MK » Wed Jul 04, 2018 7:31 am

Swap the reeds with the stock ones first.
Poorly sealing reeds cause exactly that kind of low and partial carburetion issues.
Bye
Martin

hondaror
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Re: end cans different tempreture after ride. whats the caus

#11 Post by hondaror » Fri Jul 06, 2018 3:54 am

You might want to consider a Uni-syn. Carbs set up with them ensures the engine runs very smooth.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

graham heise
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Re: end cans different tempreture after ride. whats the caus

#12 Post by graham heise » Fri Jul 20, 2018 5:09 am

I did some more adjusting and checking. first i changed to original steel reeds and re-set the carb balance using drill bits under slides. still the same result, left chamber hotter. did change the power delivery a little, mainly smoothed the lower to mid range throttle. Next i bought a lazer guided infrared thermometer($40 ebay), went out testing and yes left chamber hotter. checking just under the rad gaurd about 70mm from cylinder i was getting temps around 190d celcius leftside 180 right side, at the end can it was 55 left 47 right. i tried speeding up right side carb adjustment. yes got the temps close but carbs where out of balance checked through the carb sight windows.
I am still scratching my head. i have just cleaned and rebuilt some 31k carbs to try next. i will be paying close attention to float heights.
Just because i have the new thermometer i took my rz out for a run and took the temp gun. guess what similar result. left hotter then right.
I have just finnished rebuilding a ported 31k engine to swap into the rz as the one in it has done 10000 hard k's and is getting tired. i finnally bought all the bits for a leak down tester and i will be testing all these engines and maybe i will find a small leak on the left side of the ones running hotter.
Hey Rory does the uni sync fit in an lc with air box in place? does it's float tube need the be verical? may be hindered by frame ? I'm thinking of buying one. The elderbrock model. Just concerened about fitting in the limited space behind and above the carbs. thanks G
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hondaror
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Re: end cans different tempreture after ride. whats the caus

#13 Post by hondaror » Sat Jul 21, 2018 3:49 am

If you take the boots out, you should be able to get it in there. Yes, the tubes should be as close to vertical as possible, but make sure it remains at the same angle for both sides.

Another concern, were either of the pipes the receiver of aluminum from a piston breakdown or meltdown? There could be aluminum in one pipe that is also causing your issue.

How is it running? Are you over thinking this? Is it possible you need to jet the cylinders differently? Are the plugs running the same?

The unisyn will be sure your engine is pumping each side at the same rate. Your drill bits can't read that info.

Good luck with figuring things out. Keep us posted.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

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Re: end cans different tempreture after ride. whats the caus

#14 Post by MK » Sat Jul 21, 2018 12:29 pm

Problem solved: 5 or 10 deg C is not what I'd call a difference - that'd be kind of normal deviation between identically set up carbs.

What you could do is to play with different air screw settings left/right.
Try to get it 1/4 turn out on one side and measure again. If "difference" got bigger, turn 1/2 in on the same side and they should match better than before.
Bye
Martin

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Re: end cans different tempreture after ride. whats the caus

#15 Post by seahorse » Mon Jul 30, 2018 7:36 pm

The bike looks good Graham and you have the basis for a solid bike with the crank work and pipes.
Going back to OEM reeds that seal properly was a good step. On this subject RZ 350 OEM reeds are larger and can be made fit with a hand machining with a file if you ever have the top end off in the future.
Re the temp difference. I think Bare was onto the worst case scenario if your crank was not trued before install then this will account for timing difference. But alas a job for next time if you ever do a complete tear down.

Things worth a try are plugs, simply swap them over, or if your leads are long enough you can simply connect them to the opposite side and try that.

Re the carbs be carful swapping out carbs on a bike that is running well.
You can use the 31k stamped 83/84 RZ carbs with 5k1 needles but again go right through them with a fine tooth comb, checking mains, pilots, needles and seats, and setting float levels with the clear line method. With those pipes I would be using 25 pilots,240 mains and start with 5k1 needles at mid clip.

Re balancing carbs, after years of mistakes, float levels are crucial, slides coming off the stops at exactly the same time are crucial, and throttle stop adjustment there after must be the same.
If you can get a mirror and a torch to see this happening is better than a drill bit.
A feel in to see if the slides are topping out in the same position is crucial as well.


If you want to improve the bike further get a good rear shock and a 31k front end.
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