Husqvarna 51 Top End Rebuild

[dsell]

Like I needed another project, I bought a Husky 51 for $40 off craigslist.

1. Test compression. 1st time 115psi, 2nd 120psi
2. Test spark. Bright blue, never missed a beat.
3. Notice starter doesn't recoil well.
4. Notice fuel cap is leaking.
5. Remove starter and tension recoil spring.
6. Remove air duct screw.
7. Remove carb and intake.
8. Impulse grommet was bad and a piece was floating inside.
9. New intake and impulse grommet, pulled limiter caps off carb.
10. Changed gas to 32:1 and installed new designed fuel cap.
11. Saw fired in 3 pulls, but just doesn't act right. Acceleration was poor, wouldn't idle. Adjusted carb several times but didn't help.
12. Pulled fuel filter out of the tank and it looked dirty. Put a new Husqvarna filter on and it seemed loose on the hose.
13. Replaced fuel hose.
14. Took Zama C1Q carb apart and checked filter, ok. Checked gasket order, ok. Checked inlet needle setting, ok.
15. 2nd running test, same as before.
16. Was going to change the coil and decide to test spark again. Spark plug was sparking internal verses across the electrode.
17. Tested a new spark plug. Red spark, but consistent.
18. Installed new spark plug and the saw woke up.
19. Tuned the high side to 11,500 RPM, low at 3500 rpm.
20. Ran some test cuts and tweeked the tune.
21. Just doesn't seem like a 50 series Husky. Either too weak on compression or the bad coil wire is taking away some power. I've also seen bad coils kill the power.
22. Chain curved through the wood on test cuts.
23. Evened up the rakers and sharpened the chisels.
24. Drive sprocket badly wore out. Replaced the drive sprocket and greased the drum bearing.
25. Noticed the air filter doesn't fit tight in the grooves. Chinese knock off?
26. Checked spark arrestor screen.
I'm going to cut a load of firewood tomorrow and I will see how it does. I really suspect it will need a new coil. I don't think the coil wire can be changed. The piston looks good on the intake side, but it could be worn out. Here are the pictures https://husky51.shutterfly.com/

 

[dsell]

I took it cutting last weekend and it was a total dog. I pulled the cylinder last night and it was extremely fried. Heavily scored on the exhaust side and the ring was almost worn in two on that side. The piston is loose in the cylinder as well. It even wore down the piston on the intake side. I have never seen a piston and cylinder that bad and still run and cut wood!
I installed a nice used piston and cylinder from another 51. Set the squish at .025 and opened the muffler a bit. It's extremely strong now. Pictures added on shutterfly and here are two links to test cuts. The rakers are WAY too low on the chain, but that's the way I bought it.

https://husky51.shutterfly.com/

 

[Donnieboy]

Those 51s are nice little saws! I rebuilt on a couple months ago. Was scored due to the plastic intake "manifold" threads had stripped out and it was sucking air badly. New AM top end seals fuel line etc. she ran like a top! You will enjoy it!

 

[dsell]

I've always liked this series. I'm anxious to cut firewood with the 51, 346XP, and Dolmar PS540. I've ran the 346 and 540 on the same days. The 540 has a unique feel to it that can only be described by running both saws. My 028 Super had the same feel, must be a German thing. The 540 has an edge on the 346 when the chains start to dull. Donnie, are you the one with the 3 step video to the 51 rebuid? If so, you do a nice job. I was reading the comments and noticed the piston pin clips are suppose to be in a certain rotation. I never heard that, and still don't understand how they should be. A picture would be nice.

 

[Donnieboy]

Lol no I'm not that Donnie....I've been asked that before. He does good videos that's for sure! As for the c clips in not 100% sure how they are supposed to go....I just make sure they are fully in the groove

 

[dsell]

Broke the starter today. I was afraid this would happen since it was pulling so hard. Checked the compression warm after this happened and it's 150 per my gauge. That seems inline with what other people test.

 

[dsell]

Noticed something else. This Mahle 46ZD5 is original and 44mm model 51.



I replaced it with a Mahle 46ZD5 46mm cylinder. Someone mentioned that in another post and these pictures prove that you can't go by the 46 in the Mahle number.