Cost will depend on who you use and how much “extra” you want. Parts are just over $500, and I use P1 Engines, and pay around $500 for Labor, Break-in, and Dyno, so a little more than $1,000. But along with that, I can text/call/email Jesus at any time and typically get a quick response for help.
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$500 must include a rod kit. There’s no way a KA piston kit is that pricey. Would make sense regarding the labor figure at that point too.
The rod alone is $400 so prob not included at the $1k rebuild price. Rods seem to be items to inspect and only replace if there are signs of issues. My last rebuild on one of my motors the builder split the crank and inspected everything but chose to continue with the same rod and simply replaced upper and lower rod bearings not the rod itself.
Top ends in my experience are $600-800 with dyno/ break-in.
The more major service I just mentioned with splitting the crank, replacing rod bearings and a more in-depth bottom end was $1100. Add a rod to that and you’d be around $1500.
Yikes, I was off base…but even looking at the USA retail price list the parts for a top end are still only $250 included gaskets and o-ring. @Zebug is P1 charging above retail for parts?
The cost to maintain a single-speed race engine still blows my mind, and is the reason a switched to shifters back in 2010. Granted that was in the Stock Honda heyday, but even a Rok Shifter piston kit + cage bearing is $155 from PSL today. Switch to shifters. You know you want to 
oh wow. so a bottom end is only $1100 compared to about $700 for a top end. would it be more cost effective to just buy a new engine about 15 hours after your first top end? because then you would probably need a top end and a bottom end which would run about $2,000 and a new engine is just $1,000 more.
For just a top end? I’ve had 3 different builders for my KA’s and they’ve only charged $600 at most for a top end including dyno. $1000 should be a full rebuild
What’s the purpose of the dyno? Just a verification of the power or does it include engine break in?
Power depends on the carb setting & exhaust… I’m just wandering
Little bit of both. Dyno will include a break in, you can’t dyno a motor that hasn’t been broken in, and it also gives updated info on things like powerband. Sometimes after a rebuild the engine gets a little stronger or makes some power in a different area rev range, so having a relatively updated dyno sheet is always convenient.
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I guess it depends on what parts alone are being changed. All prices I am charged is retail, but typically more is replaced than just the piston. The reeds get changed, carb rebuilt, and it actually looks like the last time had the main bearings and seals replaced as well. The time before would have been $700 for the top end. I just didn’t look at the full itemized list because I sent it for the top end, but since he does a full inspection, he felt there were more to replace.
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That $700 sounds more reasonable. I usually just send in the motor and say “Do what you need to do and let me know what you did when you’re done.”
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Do we have list of engine builders per state? I’m looking for one in Florida.
AM Engines is in Miami. Anyone have dealt with them?
Looks really expensive, but I can also see how it all adds up. Evan is not wrong on the shifters though, although it also depends who does what. I can totally see the $500 for labor, break-in and Dyno on a top end, takes a lot of time and equipment cost. I run KZ and I do all rebuilds myself (except crank splitting/balancing), about $100 all included for a top end ($80 for the original TM piston kit, $15 bearing, $5 consumables). But if I had to pay myself $100/hr and amortize the tooling cost (gauges, micrometers, etc) well that bill would go up pretty quickly. Takes a lot of time too
I remember the market price for engine maintance in the US (i did Uni in Miami) and i have always thought they were completely out of control.
In Europe, a piston change will run you around 200 - 250 EUR, including the piston itself, and that is being generous.
It literally takes someone 1 minute and a half to change a piston and check clearance.
Not to discredit anyone, but you do not need someone to break in your engine on the dyno, and i guarantee you also don’t necessarily need a dyno graph for a spec class.
Today’s manufacturing technologies allow you to run in a piston within 5 mins tops, on the track.
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That’s what I do as well. I tell him about how many hours, at least a top end, anything else it needs (clutch, pipe, etc) and have him let me know what else is needed.
I did the piston on our last Mini Swift myself, Just a little hard to find an inexpensive hone that fits it. I did think about doing basic rebuilds for the local club racers at a reduced rate compared to major builders, all in an effort to cover the cost of the tools needed.
I pulled my first KA out of the box and my builder said “go easy the first session” so I wrung it out to 16k+ on the out lap and beat the snot out of it and then ran it the whole rest of the season without rebuilding.
YMMV. But they don’t offer break-in sessions anymore at most races. Simply not as necessary anymore.
The builder dyno’ing it to break it in is a nice thing though, if you have limited practice time and need to hit the ground running at the track. And for the large population of karters who still think that the engine is a huge piece of the puzzle in a spec class, the dyno sheet helps ease their anxieties.
My best running race bike was “broke in” in an absolute mud fest at a track with volcanic ash for dirt. Only prep I had done to the bike was a suspension bearing lube.
Having seen both sides of the pond, here is my point of view, for what it’s worth. Cost in US is not comparable to cost in EU (or Italy for that matter since you are close), there are factors outside karting at play. Same thing when you bring a car in for a checkup or compare a brake job on a sedan in US vs Europe…so take that part away as it’s apples to oranges. In general, professional services are much more expensive here. Back to karting, in terms of “what” is performed, my view is that in US there is too much reliance on dyno, too little on field tuning. I don’t mean to say it’s an engine tuner issue, rather it’s a customer preference. Typical Italian/European customer pays the big bucks to get the stuff from Palazzi, Savard (insert big name here>), so when equipment is the best, it’s then all about field testing/jetting etc. from there. Customer in US wants to see the dyno run showing how much more power the engine makes to pay the premium.
Again, I’m not saying it as a blanket statement, top racers and tuners know what they are doing, I’m talking the general consumer who accounts for the majority of the sales. In turn, tuners adjust their business models accordingly. Last time I asked my (Italian) tuner about a dyno run, he told me to F*** off, here they put a price tag on it, which reflects time, equipment and expertise invested in it. Maybe too much reliance on SPEC classes and trying to find the diamonds in the rough?
I don’t think the dyno services here are about having a comparative number to brag about, a lot of the builders don’t even provide a dyno sheet cause every dyno is going to read differently. What it’s about is spending the time to maximize the carb tuning and provide that baseline tuning to the client so that the guess work of finding that tube isn’t required, the engines are fast out of the box and only require small tweaks for weather changes.
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One certainly could go with that process, but I don’t think it’s a good way to go on anything other than your practice engine.
I’d expect the following from a top end service and it’s more than a minute or two:
Bore size and ovality check.
Hone to bring bore back to true and create the crosshatch to help with breakin.
Throughly clean cylinder.
Swap piston.
Replace base gasket if needed.
Verify port timing and squish clearance per spec to account for any variances in piston pin or crown.
Sure, you can skip some steps, but I think it’s fair to say doing so is not best practice.
Although I’ve never bothered myself, a dyno run seems prudent as a final QC. Doesn’t have to be a measured run with a curve. I can see how just getting a load and heat into it before its shipped out gives peace of mind.
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would it be cheaper just to rebuild the top myself? and not worry about dyno and break the engine in myself