Working on a ground-up restore of a Canadian '85 RZ350 and had some questions regarding a starting point for the jetting. Here are the mods:
- Mild porting/polishing
- Stock carbs; Canadian versions did NOT come with the PowerJet carbs and come with 185 main jets and 25 pilot jets
- Toomey pipes, Toomey Perfect Jet Kit (this is made for the US version with PowerJet carbs), Toomey 2:1 high performance air filter system, Boeysen Reeds
- Zeeltronic ignition system
- Stock oil injection retained
I'm wondering if anyone had experience with this or similar setup and if so, what would be good (read that as SAFE!!!) starting point?
Thanks in advance.
1985 Canadian RZ350 - Jetting question
Moderator: rztom
Re: 1985 Canadian RZ350 - Jetting question
The US carbs do not have "power jets" 1984 or 1985.
The Toomey Perfect Jet Kit came with 410 & 420 mains
Dynojet DN0404 needles clip position 3
Pilot was #20
I have a US model 85RZ350 that has mild porting, Toomey Pipes, Toomey Air Cleaner with Y-pipe and it runs well on this jetting spec.
I believe the stock main jet was a 230 on the USA model VM26 Mikuni carbs.
The Toomey Perfect Jet Kit came with 410 & 420 mains
Dynojet DN0404 needles clip position 3
Pilot was #20
I have a US model 85RZ350 that has mild porting, Toomey Pipes, Toomey Air Cleaner with Y-pipe and it runs well on this jetting spec.
I believe the stock main jet was a 230 on the USA model VM26 Mikuni carbs.
-
bstewartca
- Posts: 19
- Joined: Thu Jul 05, 2018 1:33 pm
Re: 1985 Canadian RZ350 - Jetting question
Yes, I actually have 2 air boxes.
1985 Canadian RZ350 - Jetting question
I recommend putting the stock carb parts back in, the airbox back in minus the rubber snorkel, and upping the main jet by two, maybe three.
The jet kit is meant for that air filter setup, and to go into a US bike. You’ll see little gain, much more noise and horrible gas mileage by using it over a basically stock setup with slightly increased main jets
The jet kit is meant for that air filter setup, and to go into a US bike. You’ll see little gain, much more noise and horrible gas mileage by using it over a basically stock setup with slightly increased main jets
Re: 1985 Canadian RZ350 - Jetting question
An overly restrictive airbox will mostly show its limitations at upper rpm.
While it is true that a stock airbox will quiet the bike down it is much harder to say for certain that you will get better power with the airbox than without. A system like the Toomey Y-pipe + Airfilter is likely going to return better high-RPM power than a bike equipped with a stock airbox.
Airbox resonance tuning depends on an increase or decrease in airbox volume or increase/decrease on inlet pipe length or diameter as peak horsepower moves UP/down the RPM scale.
In other words, if a stock airbox is tuned to deliver peek resonance efficiency at 8500 rpm and you add pipes that are tuned to deliver peak power at 9500rpm, then the airbox resonance may deliver lower than expected power at 9500 rpm. On the other hand you will probably still see big gains at 8500 and you might even have better throttle response at lower RPM. But peak RPM HP will generally be lower than without the airbox. Further, you may also find that power drop-off at high RPM (over-rev) is more pronounced with an airbox than without.
So the decision has to be made based on personal preference and actual testing.
Not many casual testers are willing to spend the time removing and reinstalling the airbox and re-jetting the carbs for back to back comparison. In fact, most riders will have made other changes between dyno runs that will render the comparison moot.
As for gas mileage, more out means more in. Hi performance two-Strokes were never designed for gas mileage. If you take a stock RZ that made about 35-40 HP and add pipes and a jet kit, the output jumps to 60+hp
I personally think the drop to around 20mpg is worth it. My plugs don't foul, I don't have rich condition blubbering.
While it is true that a stock airbox will quiet the bike down it is much harder to say for certain that you will get better power with the airbox than without. A system like the Toomey Y-pipe + Airfilter is likely going to return better high-RPM power than a bike equipped with a stock airbox.
Airbox resonance tuning depends on an increase or decrease in airbox volume or increase/decrease on inlet pipe length or diameter as peak horsepower moves UP/down the RPM scale.
In other words, if a stock airbox is tuned to deliver peek resonance efficiency at 8500 rpm and you add pipes that are tuned to deliver peak power at 9500rpm, then the airbox resonance may deliver lower than expected power at 9500 rpm. On the other hand you will probably still see big gains at 8500 and you might even have better throttle response at lower RPM. But peak RPM HP will generally be lower than without the airbox. Further, you may also find that power drop-off at high RPM (over-rev) is more pronounced with an airbox than without.
So the decision has to be made based on personal preference and actual testing.
Not many casual testers are willing to spend the time removing and reinstalling the airbox and re-jetting the carbs for back to back comparison. In fact, most riders will have made other changes between dyno runs that will render the comparison moot.
As for gas mileage, more out means more in. Hi performance two-Strokes were never designed for gas mileage. If you take a stock RZ that made about 35-40 HP and add pipes and a jet kit, the output jumps to 60+hp
I personally think the drop to around 20mpg is worth it. My plugs don't foul, I don't have rich condition blubbering.
Re: 1985 Canadian RZ350 - Jetting question
I've done that, and so have others. Airbox to Y-boot/filters to Airbox. Hence my comments...brrrappp wrote: ↑Thu Dec 20, 2018 12:28 am So the decision has to be made based on personal preference and actual testing.
Not many casual testers are willing to spend the time removing and reinstalling the airbox and re-jetting the carbs for back to back comparison. In fact, most riders will have made other changes between dyno runs that will render the comparison moot.
^^^ Fixed. A stock Canadian bike has more go than a US bike. This is pretty common knowledge.brrrappp wrote: ↑Thu Dec 20, 2018 12:28 am As for gas mileage, more out means more in. Hi performance two-Strokes were never designed for gas mileage. If you take a stock restricted AMERICAN RZ that made about 35-40 HP and add pipes and a jet kit, the output jumps to 60+hp
I personally think the drop to around 20mpg is worth it. My plugs don't foul, I don't have rich condition blubbering.
Someone who is asking jetting questions does not know the bike very well. For ease of jetting and to avoid frustration/disappointment, on a CANADIAN bike, I stand by my recommendation. Unless you are racing the bike, the ~2 ponies up top are going to make no difference. You won't notice it while you're holding on for dear life at 9000 rpm anyway... You will notice only getting 100km before hitting reserve though.
Re: 1985 Canadian RZ350 - Jetting question
I don't totally disagree with your assessment.
Somewhere on this site or in my web-loafing, I saw a pdf of an article clipped from one of the major MC magazines where they did a test comparing the STOCK Canadian chambers to Toomey Pipes and original USA pipes.
The Toomey pipe was the best overall but the Canadian pipes were not far behind.
The test included Dyno charts from a stock RZ350 so it was a good baseline example of what to expect.
Maybe someone here knows where that pdf is located and can insert a link?
Somewhere on this site or in my web-loafing, I saw a pdf of an article clipped from one of the major MC magazines where they did a test comparing the STOCK Canadian chambers to Toomey Pipes and original USA pipes.
The Toomey pipe was the best overall but the Canadian pipes were not far behind.
The test included Dyno charts from a stock RZ350 so it was a good baseline example of what to expect.
Maybe someone here knows where that pdf is located and can insert a link?