Hidy-ho.

Got the old banger dyno'd today, flat spot when accelerating, idling too high once warm etc. and it's not looking good for engine apparently. They had a mechanic come over for a second opinion and the engine is losing power when it's warm. Starts off at about 65HP then after about the 4th run it dropped down to 48HP. Nothing wrong with fuel, carby, oil etc. Didn't get the graphs from the dyno, he must have felt sorry for me, all he charged me was $20 and that included 2 new plugs and a new fuel seat.

My question is, from an economical stand point is it better to rebuild or replace, either new or 2nd hand? I know there could be potential issues with a 2nd hand motor but looking on the interwebz I can't really afford $6 or 7K for a new one. A quick quote was around $5K for a top and bottom end rebuild. I know what I'd like to do.

Just looking for opinions or experience with similar issues.

Cheers.

 Do not know if it's the way to go, but you can buy a brand new twin cam 88 from the US for a bit over the $4kUSD mark. 

 A little bit quick on the typing, I'm not implying you want a new motor, I was just using the comparison for what they're selling for. Did see a price on ebay USA a while back and sportsters and evos motors are so cheap over there. Depending on your time frame there seems to be a fair few options.

I think you need to look a bit deeper and ask a few questions.
65 hp is almost right, maybe a touch low.
Is it wet sumping ?
How many K's has it done ? If the bottom end is sound (??) then just do cam chest + top end rebuild.

If the bottom end is good do a rebuild, as Dave said is there something not compatable, do a leakdown and go from there . Check all the basics and go from there, could be something as simple as a coil.

Yeah cheers guys. Dyno guy said no issues with compression at all. When I say old banger, she's 10 years old, 2000 Super Glide however she's been ridden hard and put away wet so to speak. Bought it from an aquaintance and I am told that he had it on loan for approx 6 weeks before he bought it however just after he bought it the engine seized. It was apparently replaced it with a 96ci but with 87K k's on the clock I can't say when it was changed over.

If she died tomorrow she'd be sittin in the garage for an undetermined amount of time until funds could be raised, hence the question which would be the most economical way forward.

Might look into this wet sumping over the weekend, I guess by draining the oil I should be able to tell. Doing some basic googling if there's more oil than what there should be would that mean it's wet sumping? Or maybe changing the oil as some have an anti-frothing additive?

Problem is i'm not a mechanics arsehole. If I pulled the motor apart for instance I wouldn't have a forkin clue how it goes back together let alone looking for issues with the parts I was pulling out. Guess I'm up for some bucks either way, I could spend dollars searching for problems or spend bucks replacing it, dilemmas dilemmas...

Cheers everyone.
DynaRider, the dyno guy said there is no issue at all with compression. I'm also a bit dubious as to whether they replaced the original engine with a 96 to tell you the truth, I'm just going on what i was told.
Might just start saving the cash and look for a low KM 2nd hand motor, 88 or 96 wouldn't worry me.

 I am no expert on Harleys but aways knew enough to keep mine on the road at the cheapest possible price so these are my thoughts.

Your Bike sounds odd if its got good compression and gettin fuel why dose it loose power when it gets hot?

Why dose it get hot ?

Is it running a bit advanced may be?

Dose it have good oil pressure if has to much oil pressure the oil will run hot.( relief valve )

 Did the mechanic give you his thoughts on why it idles fast when it is hot.

The bike will probably run a bit warmer on the dyno because not as much air flow as normal even with fan if its not making any funny noises i would try to sort the idle problem out and ride it also if the backing plate has moved a little and advanced it self it will idle a bit higher and get hot and loose power.

 My old bike done that after a rebuild you could feel the heat from the oil tank under the seat i  was gettin a hot bum and the bike would not go over 95 kms and lost power.

I would also look at anything that had been done recently if you have had any thing done on the bike in the last few months.

 It dose not sound like you need a new or rebuilt engine to you get to to bottom of the problem it may not be as bad as you think.

My old bike has done 165000 miles and when i stripped it down and measured the crank up it was still within specs and put it back in all i did was piston kit, lifters,valves,and oil pump so as long as yours has had good oil in it how bad can it be.

Dose the oil have metallic particles in when you change it. 

 Sounds like Dynarider is on the case to me or giving you a good start anyway.  

     P.S Awesome lookin ride

An engine loosing power over a period of time can also be caused by valves on the way out.

Thanks for all the replies and insight.

 

DynaRider - the engine numbers match those of the VIN or whatever, almost as if nothing was replaced. Would or could this mean that the engine was more likely rebuilt then replaced after it seized?

Carb and everything is a standard CV however the dyno bloke said it had a Joss/Yoss(?) carby kit (googled it with no result) and it was all polished. Exhaust is a Santee short shots system. Dyno bloke said it was getting plenty of fuel and that carby was operating exactly as it should be.

You say to 'definitively identify the engine', how would someone go about doing that? Does it mean stripping it down?

I'll look into a compression kit during the week so that I can rule that part out.

 

insaneryder - when  I say hot I sort of mean at riding temperature, as opposed to cold (at first start up). Bike only gets hot to the side of the legs, not under the bum.

Don't have an oil pressure guage to determine whether the oil pressure is too high. I will say that the bike has been this way since day I bought her, even the flat spot when accelerating. She'll sit on 140kph no probs and did so on a run back to the Gold Coast from Airlie, not all the way obviously.

Mechanic said nothing about the idle because it wouldn't bloody do it when they started it. It usually happens after at least half an hour riding.

I have done nothing to the bike recently mechanically wise and as mentioned it's been this way since I got her, which is only 6 months ago however it was a year ago we went to Airlie, the bloke I bought it from came with us and lent me the bike before I bought it.

It does use a bit of oil, not much though. I may throw half a litre in every month or so, between changes. No metal particles.

As you and cm364352 say, maybe after compression testing and oil pressure test I should replace lifters, valves, pistons etc before doing anything too major.

What is this 'leakdown' you refer to?

 

Once again, thanks to all for your help.

 

Just out of curiosity, would that be Powerhouse Dynotune? If so, I would trust Steve's recommendation on what should be done. IMO he's a great tech/mechanic and he'll point you in the right direction.

"Yost". I have a low opinion of them anyway, but you have one already, so no money to be lost now.
If you have a 2000 model bike, and the eng, frame, and compliance plate all have the same numbers, then clearly the story regarding a TC96 engine being installed is all wrong,
as it is clearly the same original engine.
If it previously seized, "what was done" is probably the winning question. That whole story is a little hard to follow.
I merely meant to check out the engine number if it was different to the frame, but it is not, so identification job done.
I would definitely do a thorough compression check. Pull out the plugs, and get a torch and look in the cyls. Are the good, or bad? If the compression test result is poor, think about a leak down test. This is where air pressure is introduced into the cyl to see where it leaks from, so you can tell more accurately if you have a leaking valve, or flogged cyl. There is a leak down tester, of course, but some make do by fabricating fittings.
Having said all that, testing it will not make it better(so you might not want to bother).
The likelihood of your having to, at least, disassemble the top end, is high.
At 87000 k you have nothing to lose by giving it a top end freshen up(save for the seize up story and.... etc).
Really hard to assess it more from a distance.
I suspect possible piston trouble, but, really, it could be a range(or even combination) of things.

deadwood   maybe give old skool customs a call 0410730853   he is just up the the road from you  what he cant fix nobody can

insaneryder - that's cool, I'd check all paths and options before taking that step. Throttle and everything is returning to stop no probs, just had it all replaced due to internal wiring about a month or so ago.

Thanks glucky7 and dingo. Have driven past a heap of times but never stopped in.

DynaRider, it I pull out the plugs and use a torch to have a look in the cylinders, what exactly should I be looking for?

Thanks HogBog, think a plan of attack is a compression test and a leakdown test then possibly replace the o-rings in the oil pump just to rule that part out, especially if it's an easy fix. If it's still happening then take things further with valves, lifters etc.

Sweet as bro. Chasing a leak-down tester at the moment then I'll check the cylinders. If that checks out okay then I might replace the o-rings in the oil pumps to make sure it's doing the right thing then go from there.
Thanks again everyone.

good luck mate ,any loud engine noises or whines thats more then normal .

I'll keep it in mind thanks inasaneryder. Was told by the dyno guys that no issue with compression, i'll do a leakdown test (as soon as I get my hands on a tester) and if that shows up poor will do a compression test and might take you up on the offer.
Thanks again.

Just a suggestion if I may - it was mentioned earlier in the thread to check the ignition side of things, if you can get hold of a good auto sparky get them to test your colis and leads, I have been caught out on more than one occasion with coils breaking down and have spent days trying to find a mechanical engine fault, a quad bike i used to have even had my mechanic stuffed, we did a full rebuild and no change somone suggested the coil and sure enough it was breaking down under load and getting worse with heat - pissed me off no end doing all the work to find out I didn't need to.

Coil faults can show as a decrease in power as the bike heats up resistance in the coil increases reducing spark and timing, it will return to normal when it cools again, some of the things your describing seem to match.

I could be wrong but this is just my thoughs and may be worth checking, at least it will elminate one possibility.

Sounds like you may also have to get it on the gas analyzer and sort the air mixture out.

I had mine done 3 months a go and its a different bike now it was running to lean but awesome now .

Yeah, got a bit of shit to sort out soon eh. Thanks again for everyone's help. I'll let ya's know what the fix was if indeed I find one.