R1Z is running

[m in sc]

i rode mine to work today, with this thread in mind. for clarity, mine is a stock JDM market bike, but with out the restrictors in the pipes (i sure didnt see any). however, it does have a 3xc motor in it. carbs, airbox, etc is all stock 87 TZR250.

the only thing done to my motor, during the rebuild, was i set the squish to .8mm, and used a zeeltronic cdi controller. i set my timing to be the same as a TDR up to 5k, more advanced, the used boruts curve above that.

I have 2 curves loaded, and the other one is a dead stock tzr250 curve. I can switch between the 2  and ont he stock curve, its def 'worse' in the transition. it was even worse before i had the head cut. I did go wot on it at 3800 and it pulled cleanly, in 3rd, ont he way in, anything under that it had a hard time.  (understandable). it was fine at 4-6 k than really woke up, but didnt 'chug'. IF i try to hold it there at partial throttle in like, 3rd gear, it can buck a tiny bit but isnt bad.

just some feedback.

[FZRichard]

Just checked the plugs and it looks like they may be too cold, they are BR9ES, I just put some BR8ES. See if that makes any difference.

[FZRichard]

With the BR8ES it is much better, it's at least rideable now. Good from idle to 4500rpm, then it coughs its way to 5500rpm, then there are no problems after that.

[tzar250]

I'm no expert but as a starting point, it might be worth replacing the pilot jet and emulsion tube/needle in each carb. Have you already checked the pilot jets are the correct size and the needles set to the correct clip position?

If there was any rust in your tank at any stage, particles may have accelerated the wear of jets and needles.

I don't think ultrasonic cleaning will tackle all issues - there are some very fine airways that can get blocked and would affect running.  The RDLCCrazy forum (search "brass") has threads explaining about drilling out the small brass ball bearings that block the end of the air correction circuit so that it can be properly cleaned out.  The airways are very fine - about 0.5mm diameter.  You then replace with a new 4.5mm ball bearing or tap and use a grub screw to block up.  Obviously, this could go wrong as a strategy, so worth leaving as a last resort and do some more research before trying.  Maybe try to track down a different set of carbs to try first?

When I replaced the original (but thoroughly cleaned) carbs on my TZR, with some very nearly new carbs that I was lucky to find, it sorted out any issues with the fuelling and the plugs ran cleaner.  It runs totally fine in the rev range you mention as a problem (bar a bit of vibration just at 4000rpm - which I'm putting down to parallel twin balance)

[FZRichard]

I will check the clip on the needle tomorrow. Anyone know which position on the needle it should be?

I think I have found the needle part number as 5HN23-4, don't know if I will be able to read the number off the needle but will try.

[biggz]

I will check the clip on the needle tomorrow. Anyone know which position on the needle it should be?

I think I have found the needle part number as 5HN23-4, don't know if I will be able to read the number off the needle but will try.

Hi
Part number is indeed 5HN23, clip position as stock is 4th from top (ie second richest). Needles are only available as part of the needle set 3XC-1490J-00, as far as I know. You should be able to read the number from the needle (likewise the various jets) using a magnifying glass or a jeweller's loupe.
Good luck
Laurie

[tzar250]

I'm not sure about the R1Z, but on the TZR the standard position for the circlip is the 2nd groove down from the top.

The needle code for the TZR is different, being 5L19

[FZRichard]

The needle and jets are correct. I moved the clip up one position on the needle and it's a lot better. So, it's now in the middle position.

Put some fuel in it and it looks like it's used 7 litres to travel 50km. The needle and seats are new, and the float is on 15mm. What would cause it to use so much fuel?

[FZRichard]

I am looking at replacing the piston rings on the R1Z. Are the TZR250 2MA the same as the R1Z?
Standard size rings.
Took the bike to the local motorbike shop and he says the rough running around 4500-5500rpm is due to the power valves clogged up. So, while I do the piston rings, I will clean the power valves and install new seals.
The bike passed the Roadworthy Certificate, all it needed was new tyres.

[m in sc]

i highly doubt that's the reason , its just the transition. i just rebuilt mine over the winter, everything's fresh and clean and still gets a little weird at the '5 k flat spot' .

before you tear into it, what are the compression numbers? has it been tested?

you can take an exhaust off, look into the port and inspect the power valves see how much buildup there is. 

[FZRichard]

I did a compression test and both cylinders were on around 95psi. I think I read somewhere that near 100psi was good compression.

I will remove the exhausts and have a look in there to see if there is a buildup on the power valves.

[m in sc]

i rebuilt mine at about that. cut head when rebuilt now at 140, set squish to ,8mm. yup, id go thru it if i were you, too low for my tastes.

one side was 85-90 other was 100. 





now:

[teezer250]

I am looking at replacing the piston rings on the R1Z. Are the TZR250 2MA the same as the R1Z?
Standard size rings.

The pistons and rings are the same as the r1z uses the same engine.
I would replace the pistons and rings rather than just the rings as the pistons will also be worn,also replace the little end bearings.
You need to check the bores for wear as you may need a rebore,requiring larger pistons/rings.

[James P]

Richard,

The pistons and rings are the same as the r1z uses the same engine...

This is sort of true - there have been several modifications to the pistons and rings since the original 1KT at the end of 1985. With the introduction of the 2YK (TDR) model the pattern of the rings was changed, so later rings won't fit early pistons (and vice versa). Even though ring part numbers changed again with the introduction of the 3XC (R1-Z) model, the newer rings should still fit the previous (2YK) piston. HOWEVER, I would advise not buying any pistons or rings until the engine has been dismantled for inspection - someone in Japan may have replaced the pistons and rings with NOS original 1KT parts! This obviously won't matter if pistons and rings are to be replaced together, but it would still be advisable to ascertain the size required before buying.
Yamaha only supplies standard size pistons and rings now, so aftermarket products must be resorted to if oversizes are required (although there may still be limited stocks of genuine oversize parts at some dealers...possibly).

Concerning the apparent anomalies with the performance; These may be nothing to do with the pistons or rings and there could be a chance that those parts are still in serviceable condition (so may not need replacement). It is only once everything has been dismantled, cleaned and inspected/measured that any decisions can be made about what to keep/recondition/replace. I strongly recommend dismantling the crankshaft to check the condition of the main bearings, big end bearings and big end pins (I have had several crankshafts whose big ends 'felt fine' but which had appreciable scuffing on the pins when dismantled).
One particular thing to check with 1KT-based engines is the presence of any wear (and resulting play) in the joint between PV drums - this can be ascertained before dismantling. If a standard-type engine rebuild is desired, everything can be done in accordance with the workshop manual, but a leak test is advisable after reassembly. The squish clearance is a little large in standard form, but attempting to reduce it may bring a lot of extra work for little benefit, depending on what one wants to achieve.

I don't think ultrasonic cleaning will tackle all issues - there are some very fine airways that can get blocked and would affect running.  The RDLCCrazy forum (search "brass") has threads explaining about drilling out the small brass ball bearings that block the end of the air correction circuit so that it can be properly cleaned out.  The airways are very fine - about 0.5mm diameter.  You then replace with a new 4.5mm ball bearing or tap and use a grub screw to block up.  Obviously, this could go wrong as a strategy, so worth leaving as a last resort and do some more research before trying.  Maybe try to track down a different set of carbs to try first?

The 'genuine' R1-Z TM26SS carbs shouldn't have the pressed-in brass balls - they should each have a blanking screw covering the atomiser air intake passage in the bellmouth. This screw can be removed and the main air jet beyond it can also be unscrewed, which will assist in cleaning out the passages (since they are only air passages, they shouldn't become blocked, but you never know!). The passages themselves are not that small (3-4mm, from memory) but the air jets are, so removing them for inspection is a good idea. For the R1-Z, the main air jet size should be 1.1 and the pilot air jet size 1.4.
There is something wrong in the fuelling department if 7 litres only got you 50km - you should have got closer to 150km! Moving the needle clips to the next leanest position and fitting one-grade-hotter spark plug seems to have gained some improvement, but these actions may be masking the problem. Perhaps other R1-Z owners can advise whether they have found this necessary on a standard bike... .


Judging by the comments on high-speed performance, it seems unlikely that there could be any blockage in the exhausts. However, consideration might be given to checking them for obvious defects. I imagine the 'chamber' portions contain some kind of absorption material for noise reduction, so attempting to clean them out with caustic soda or similar may not be a great idea. If TZR exhausts are any indicator, I expect the standard R1-Z exhausts weigh a proverbial ton. A worthwhile performance increase (due to increase in power:weight ratio) may be obtainable by fitting some much lighter aftermarket exhausts which have similar characteristics to the standard ones. SP Tadao, SS Ishii/Ox Racing and K2Tec have made suitable 'street' exhausts which should fit the bill (there are some others also) - I'm unsure whether all of these can still be bought new, but there are often reasonable secondhand ones available on Yahoo Auctions.

Please let us know how it pans out!

Regards,
James

[biggz]

Just a couple of things to add to James's post:

i) air jets can be removed - if not already mangled - with a 3.5mm parallel blade screwdriver

ii) exhausts are certainly weighty and do appear to have sound deadening ?mesh spot welded to the inside profile of the chambers

Good luck

Laurie