driving a factory 125 at Riverside California and share my joy with charles and some other guys from Musgrave racing … Well that is something special at my wishlist bucket !!
good day Charles .
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Here’s a question - what are good rebuild intervals top and bottom for the CR125? I see all sorts of numbers with a google search, but I’m not sure I trust them, lol.
With road racing ive gotten away with 8hr on a top end before it really wasn’t competitive and that’s sitting at 11-12k rpm for 30min at a time. Bottom end ive known some people to just put a new bottom end when they get ownership and never look back. Only time ive blown a bottom end was due to faulty case bearings.
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Jordan, are you racing with the ‘99 or ‘01? I assume you’re road racing with other Stock Honda runners. What’s the view/lived experience with your community on CR125 part availability and has there been a migration to KZ for road racing?
I can add 2c on the road racing part. Both a migration to KZ and a growth in stock Honda has been happening from what I’ve observed.
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I ran an 01 cylinder. Theyre much easier to make top end power so all of the front runners are also running an 01 cylinder. Surprisingly the stock honda class and kz are both growing at probably the same rate but I have since transitioned to KZ. Selling my honda two years ago was probably my biggest regret lol. I hope this stuff with Factory Karts with the YZ125 could be another addition to the stock moto class because id certainly leave kz in the dust for the moto rebuild intervals…
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Okay, that’s interesting on growth with both KZ and Stock Honda (and same as James’ point). Seems there’s no concerns on parts then. I take it you’re running a mixed class of Stock Honda and KZ (for road racing). If so, are you running with a weight spread for parity reasons or the same?
As to service intervals, yes, that part I get and is why I’ve been testing the 175 SS (euro version with the electric start and a 36 mm Dellorto). I’ve just done 16 hours on my last piston (mix of sprint and road racing) and 26 hours on my lower end, which still looks fine. If I’m getting that sort of life I’m struggling as to why SKUSA went to the trouble of the 175 SSE but had to drop the electric start. Had they stayed with the euro version (and the Dellorto) would the market reaction/support been different. Perhaps a question for a different topic.
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I know in the PNW there are different classes in road racing for the Honda (specifically '99) and KZ. That’s just our region so I can’t speak of elsewhere. In Sprint there is a single class which allows Honda, KZ, and some others like Rok with weight parity. The engine of choice is still KZ.
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Tom, they run in two separate classes, KZ and Stock Honda but Hondas are also allowed to run in KZ (though not very competitive) if they want to run 4 races on the weekend. Ive attached the rules for both KZ and Stock Honda classes. Again Honda is allowed in KZ but you will never see it win…
For Honda youre required to run OEM bottom end, piston and reeds. I believe it is open timing but you never really needed to go further than what the SKUSA Timing plate allowed. They did just start to allow re-plated cylinders because for a while you werent allowed but good cylinders are really scarce.
KZ class is fair game for those engines, port and polish what your heart desires but has to be under 125cc.
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Only caveat I’d add (Although it is implied, but I can see some people getting tripped up) is that the engines still need to meet KZ rules per CIK rulebook. Port height, head volume, 30mm carb etc etc.
Just in case someone turns up in the KZ class with porting set to kill and a 38mm carb… Depending on the org, they could run another class though
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Surprisingly in the UK for the 125 superkarts they run bigger carbs and the DEA 125cc is pretty common too. I dont think a 125 DEA exists in the US… But yes in my head when I refer to KZ I think FIA KZ and not as an open 125cc class.
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Yes, for these purposes when I’m talking KZ, it’s stock/FIA.
You’re quite right though on the road circuit open 125 class - we are very similar in Australia to the UK in which our 125 open guys now often (but not always) run DEAs with 39 mm (not 38) Dellortos and full variable digital ignitions. But, in that (stressed) state, they are not cheap to run and absolutely go bang, sometimes too often. There is no way I’m going there - stock is more than enough for me. They’ll also run a longer Anderson chassis, albeit there are competitive alternatives (my engine builder makes his own long circuit chassis as an alternative and they are very competitive with the Andersons). Stock gearbox is “just” the base FIA KZ chassis.
Our 125 Open class would have peaked in numbers during 2021/22. It’s now heading south - no doubt the relatively high running costs are a big part of the reason. This is why a fun accessible stock gearbox class is so important. But for that we need a decent stable engine package. Stock Honda was brilliant until it wasn’t - a great shame. But, self-evidently, there’s still strong support (perhaps more in road racing than sprint) despite Honda/HPD pulling the plug. Nonetheless, with no new CR125 engine builds, we need to find good alternatives. Stock KZs and/or the 175 SS have to be part of the answer.
Jordon, thank you for the class information. Which is your series? Also, can you share your typical road circuit stock KZ carb settings (for the 30 mm Dellorto), particularly for your track/s with the most WOT (where engines can get somewhat hot and bothered).
Carb settings typically change between manufacturers but theyre in general pretty similar. I can only speak for Modena since that is what I run. Ill run a 270 emulsion tube with a k28 needle, 55 slide, and main jet usually around 160. I can speak for pilot and inner pilot since I do not know them off the top of my head (most of the time I never touch them) and wont have access to it for another month or two since I am out of town. We also run a heavier float weight and dont run a flow back to the tank. Just the fuel pump to the carb and thats it. Heres a photo of the engine setup with fueling and a video of the modena kk1 at my local road course which is flat out majority of the lap. I was toying around with my gopro so the camera angle isnt so great…
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we need to find good alternatives. Stock KZs and/or the 175 SS have to be part of the answer.
If you want another reliable alternative I would not look for KZ. The maintenance usually adds up to about double what the honda is and much easier to go kaboom. Honda was nice for the beginner cause it would still run good on slightly rich jetting and wouldn’t blow up instantly if you accidentally go a little lean. Ive been seeing some good results with the 175 longevity wise but again its also faster than a kz which some people already shouldn’t be driving that fast.
Theres another thread on here regarding Factory Karts and re-introducing a moto engine with new yz125’s and other cc’s. I really hope they take off and prove to be reliable on a kart because id love to go back to a reliable and maintenance (relatively) free motor.
Restricted KZ should be the option people are exploring.
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Maybe a Factory Z125 instead?
I always wanted to test running natural gas in a 2 stroke kart. The reduced airflow would reduce power, it’s extremely detonation resistant, and it costs the equivalent of 23 cents per gallon!
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Thank you Jordan. Really appreciate that. I take it you run with the AKRA?
Stock Moto is dying/dead unfortunatly with the main killer being lack of parts. If you are after a cheap shifter engine, look at an older TM as others have said, IE K9B, K10B, etc.
The Factory Kart program is interesting for sure, but it will need to get support from alot of places/series to become anything sustainable. I would personally love to see a stock 250 class!
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AKRA and WKA mainly!
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