Engine advice? 

"ptak appreciates old racecars" (racecarptak) 06/10/2015 at 10:11 • Filed to: clueless person asks for help

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So I’m thinking about buying an engine (hope the link works):

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For my moped project. It looks dirty and dented on the outside, but I’ve heard that’s hardly a sign of what the inside is like, plus new ones cost more than I can afford.

My question is, what should I ask the seller about? All the listing says is it has compression.

It’s my first project as a whole so I’m generally clueless about this stuff. Thanks

(old 5-series for your trouble c:)

SidewaysOnDirt still misses Bowie > ptak appreciates old racecars 06/10/2015 at 10:12

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Pretty sure you just need an LS swap, bro.

ptak appreciates old racecars > SidewaysOnDirt still misses Bowie 06/10/2015 at 10:14

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Or a 2JZ swap, breehhh~

64Mali > SidewaysOnDirt still misses Bowie 06/10/2015 at 10:16

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LS is overplayed I think we need turbo 4 swaps now, or electric motors.

ESSSIX GmbH - Accountant/Wagon Thumper > ptak appreciates old racecars 06/10/2015 at 10:16

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Id ask for oil from the block and send it out for testing.

http://www.blackstone-labs.com/

PS9 > ptak appreciates old racecars 06/10/2015 at 10:20

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I thought you were going to turn an old BMW into the worlds first 2 stroke two cylinder diesel german. I am dissapoint now.

Funktheduck > ptak appreciates old racecars 06/10/2015 at 10:21

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Engine has compression, but is it the right amount? Say it’s supposed to be 10:1 but it’s actually 5:1. It still has compression by definition.

Ideally you would have video of the engine running before it’s taken out. Check for any fluid leaks or signs of leakage. If it’s overly clean or recently been repainted it could be because they wanted it to look spiffy to sell or it could be an effort to hide issues. If you can see it in person life will be easier and you can take a compression gauge with you. If not, see if the seller will video it for you.

Buying an engine sight unseen is like buying a car the same way. It's risky but you can defer some risk with lots of photos and/or video. Ask for service records too

RamblinRover Luxury-Yacht > ptak appreciates old racecars 06/10/2015 at 10:38

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Like with any gas engine, the three elements are compression, fuel/air, and spark. The most common one not to have for whatever reason is fuel, but spark can be a problem too. Spark is probably fine in this case, though, given that I don’t see a fancy electronic setup like on some Kohlers. That means to get it to run, you just need to sort out whatever may be wrong with the carburetor - often this is clogged jets or a sticking float valve or any number of things like that. I’m curious as to how it got to its present state, though - it looks like the exhaust and some intake pieces were taken off, which suggests a swap to a newer engine. Why?

One of the trickier things that happens with some Briggs engines is shearing the flywheel key, so compression and fuel are both there, but the spark is timed wrong. Maybe what happened here, and he couldn’t figure it out... maybe. Or, it may just be tired and smokey and he’s replaced it with a fresher one.

At any rate, having compression is hopeful, but a couple things here make me raise an eyebrow. Even if it’s generally okay, you may have to have the front cover off to get it running, or the carburetor completely disassembled.

Echo51 > ptak appreciates old racecars 06/10/2015 at 11:01

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I would get something more suitable for revving, aren’t these mostly “work” engines for lawn mowers and lawn tractors, where RPM’s are constant and not more varying like a moped engine? Maybe engine+gearbox off a cheap dirt bike or quad?

ptak appreciates old racecars > Echo51 06/10/2015 at 23:45

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That’d be easier, but all small V-twins look too ugly :P Plus it’s been done before, you can plug in a torque converter and you go down the road with no problem.

ptak appreciates old racecars > Funktheduck 06/13/2015 at 09:21

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Thanks for your advice. I hadn’t thought of the compression issue. I may have to go take a look at it, even if its 200 km away :P

Funktheduck > ptak appreciates old racecars 06/13/2015 at 09:24

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Probably wouldn’t hurt to look the engine up on the Internet for common problems to look out for if any.

Good luck

ptak appreciates old racecars > RamblinRover Luxury-Yacht 06/13/2015 at 09:25

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Thanks a lot for your advice! Excellent deduction there with the exhaust.

I’ve been looking at a lot of other listings since, so I’m not so sure about this one now. But you’ve given me something to think about when I look at it or others again.

ptak appreciates old racecars > PS9 06/13/2015 at 09:25

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That’s an ongoing project, actually.