I had a head gasket leak so while replacing the gasket I went ahead and put a new piston and ring set in (wossner 8815DC). I also had a reputable shop in my area take the head apart to make sure nothing was warped and to re-seat the valves, they re assembled the head and I went ahead and started putting the bike together. The cam chain was replaced by previous owner right before I bought the bike and was 3 clicks out on ACCT about 500 miles ago when I installed the ape MCCT so I didn't replace the chain. I have now tried setting the timing 5 times and still haven't gotten the bike to start. I am beyond frustrated and it's starting to affect my college studies (engineering). I tried calling uptite and was told to make sure piston is at tdc by putting something in the spark plug hole and not just relying on the crank marks, I still cant get it right. I'll include pictures of my latest attempt.
Your timing looks right to me. Is there a particular reason for which you think that it is the rpoblem? Considering that you've replaced the piston, maybe there's something wrong with it? If, for example, you haven't checked its size, maybe its diameter is too small and there's too much piston-cylinder clearance and therefore not enough compression (although it sounds unlikely to me). I mean, if the bike worked before (except for the leakage) now something must have changed. Are there other not OEM parts that you have installed?
The piston and ring is the only non oem change I made to the engine. The piston is a wossner and was labeled as for this bike (model and year, 97.76mm std bore and std compression ratio part number 8815dc). I will try and get a compression tester to rule out the piston and or poorly seated valves. When starting the bike revs just barely like 400-600 rpm and will just stop once I let go of the starting motor. If i was close to a husqvarna dealer or mechanic like uptite I would have taken the bike in already at this point, but I’m in Iowa. I’m not sure what to do.
Wossner pistons... OEM is twice as much but so is the durability. Anyway make sure you check valve clearances when the auto decomp isn't engaged. Take a break from the wrenching, don't stress too much about it unless you absolutely need the bike running. Calmer mind helps solve problems
The point is that, as far as I've understood, companies which manifacture engines machine cylinders without exceeding a tolerance, like it usually happens with mechanical parts in general, but then they measure the diameter of each cylinder and select a piston, machined within a tolerance, too, suitable for the hole in the cylinder. I expected to find some dimensions available for pistons and cylinders in the parts catalog, but I didn't. Usually when you replace a piston you are supposed to measure the diameter of the cylinder or read it on the cylinder and then buy a piston which will give the proper clearance. I still think that it is unlikey to be your problem because even if you had a hole in the cylinder at max value and a piston diameter at minimum value, the clearance should still be less than the one you can find in worn components, because those tolerances are tight. I would be more worried if the piston was too big because then there would be a possibility of engine seizure, although still a little possibility, I think, if in the 610 the tolerances are as tight as it usually happens with other bikes. Here you can find an example of pistons being offered in different sizes to match a specific value. Wise tip!
did you check piston to bore and ring gaps? I hardly think a new piston would create starting issues if everything is within specs check spark and carb? if it has one that is! could have just not done something simple when putting it back together. hope you figure it out. definitely take a step back if it's stressing you though. it's not good to work on a bike when you feel like burning it to the ground haha
Thanks for the replies guys I’m young and can use any advice I can get. I brought my bike to an older friend who had an attachment on his air compressor that could thread into the spark plug hole so we performed a leak down test at 70 psi and sprayed some WD40 around the valves. Every single valve had air bubbles coming out. The bike only built about 80 psi with a standard compression tester. I now am going to take my bike to the shop that removed and reinstalled the valves to see what they can do. I don’t at this moment think the piston is the problem. All the shop did was strip the head down and check to make sure it wasn’t warped or cracked. I’m wondering if they mixed the exhuast/intakes up when reinstalling. This has been quite the headache but I’m hoping this gets me on the right track.
I don't know whether 80 psi is a good value, but I guess you have checked the manual. The other test to the valves sounds pretty demanding to me, though, because usually people just fill the chamber above the valves with fuel and check whether it leaks and the only pressure is generated by the weight of the gasoline, like this man does with brakes cleaner @1:25: View: https://youtu.be/reAuAbazfOc?t=85 Maybe it's normal that at 70 continuous psi they leak. Anyhow, if you are going to remove the head again you will also remove the cylinder. If I was in your shoes, I would ask the shop to measure its diameter and maybe even the piston. I wouldn't have suggested it, but in case you are going to disinstall those components anyway... . They are different and they look different even when installed because the exhaust valves have bigger heads. I have never mixed them but I guess it would be easily noticeable. Since it seems that the valves maybe don't seal very well, have you checked their clearance when you reisntalled the head? If you don't have some clearance the rocker arms will push the valves stems.
When performing the leakdown test the valve cover (which houses the rocker arms) was removed to ensure that the valves were under the full sealing force of the springs so the clearance (which I have been checking) wouldn’t be the issue. Uptite told me on the phone that hearing air hissing past the valves is not good at 70psi. I’ll let you know what I find out tomorrow after taking the husky to the shop that did the head assembly.
I'm just wondering what does the Balance shaft has to do with Cam timing? Those dots on gears are irrelevant to engine running, when I got my bike balance shaft was misaligned but bike still ran! timing mark is on the Left side, flywheel to engine case. They use special tool to set TDC but there is a notch in left case half that supposed to line up with "T" mark
And I just happen to find a pic from my engine rebuild this winter. I would check spark before you go nuts chasing your tail, even with slight leak around the valves it should start, or at least try starting. Sorry didn't read the whole thread, assuming you adjusted valve lash after assembly? Did not assemble motor at TDC and then rotated the cam?
I checked the flywheel marks to see if the crank dots were not representative of tdc mine do line up when the flywheel looks like that. I brought the bike into the machine shop today and was told that I have bent intake valves. When I did the leakdown test with my friend both the intakes and exhausts had wd40 leaking out of them so I’m wondering why the shop only found a problem with the intake valves. I’ll include pictures. Where can I buy new valves for 2006 husky 610?
That is a lot of carbon buildup for the head that was just rebuilt by machine shop... this is what my head looks like after machine shop was done with it
Should I be sending my head somewhere else? How much did that cost to get the head reconditioned and did you put new valves in? I think this is the valve I need but I’m not sure https://www.ebay.com/itm/232682127199. When I get new intake valves can they just be lapped in or do I need to ask for a 3 angle valve job. When I was talking to the machine guy he made it seem like he was just going to pop the new valves in and send me on my way.
I did my own cleaning to save the $$, then paid someone I know to do the valves. he usually charges few hundred for those single cylinder heads, specializes in high end race work so I really don't know how much he would charge if you sent it in as is, but this was already broken down and cleaned so he only took $150 from me to cut the valves and seats, also I know the guy... I used to pay $200 for a 4 cylinder 16 valve head to clean, resurface, full valve job including setting the clearance (shims under cam) but that shop closed when owner retired and moved to FL, last place I went charged me $350 each for a half-ass valve job on a 8 valve heads, basically I spent $700 total to have 16 valves done (pair of American V-8 heads)... oldtimers are retiring and new generation wants to get rich quick, but they don't have skill or patience. Guy I used for this Husky told me he once did a Porsche RSK motor, it's a 4 cam bevel drive, supposedly takes 40 (That's Forty!) hours to assemble... I don't think I can spend a whole day on same project, nevermind a full 40 hour weeK!
I ordered some new intake valves husqvarna part number 800080531 I'm going to have the machine shop lap the new valves in. I really hope I can set the timing correct this next time i'll take pictures of the crank dots, flywheel position, spark plug hole and cam gear dot and have you guys check it out before I try to start it. While waiting on the parts i'm going to try and clean the head up like how MATOC's looked. Thanks for all the help so far guys I definitely need it.
In my EFI 610, when the two dots are aligned the engine is at TDC. In the attached picture I was pulling the conrod, keeping it at TDC. It sounds quite weird to me. As I've already written, if the engine worked before, something must have changed and I don't think that both the intake valves are bent now. I really hope that the bike will work, but -sorry to write this- I don't think that they are your problem. Another possible cause that occurs to me is that on the camshaft there is a centrifugal decompression system which could be malfunctioning. Maybe for some reasons it doesn' work, or vice versa it stucks in the decompressing position even when the engine catches. But again, how likely is it to have started malfunctioning right now?
I think the decompression mechanism is working it rotates freely and has the spring attached correctly. I think what happened was I must have been off on the timing the first time I put the bike together which bent the intakes. Then all my other attempts wouldn’t work due to the lack of compression. The machine shop guy put the intake valves in a lathe and spun them to show me that they were wobbly and therefore bent. When I set the timing this next time I’ll take a bunch of pictures so that everyone can see clearly if it’s right or not.
