Hi guys i got a few ? for you. I'm currently rebuilding my stock 1200 i have the hole bottom end done and now building the top end. there is so many choices when is comes to pistons. I've been looking at the Keith black dome top pistons
9.1 compression and there 0.20 over. I guess my question is what do you guys think are they any good? and would i have any problem with going to 9.1 compression

 

No problems but you have to have follow strict break in riding habits or they will scuff the piston skirts . KB's are forged pistons so most shops set them up a little tight ( .0015 - .002" ) and that makes them very sensitive to heat and bad oiling for about 1500 miles , seen a lot of trashed ones . Any cast piston for general use in a shovel is more forgiving and most run 8.5 -1 and a bit looser ( .003" to .004 ") so break in is faster and and you won't notice the difference performance wise . Another plus they tend to be 1/3 the price .

I'd do a good valve job and have decent high spring's & collars done now so the bigger cam you will want to put in later will be a drop in instead of a headache

 

so what brand of cast piston would you recommend?

 

Most the cast pistons for shovels are imports anymore unless you go the big brand names and then your paying for the name not the quality . You go that route check with the shop who will be doing the cylinders for you . Best to let them match things anyway .

I've been using Truett & Osborn out of Kansas for years for this stuff good work more than fair prices and had no troubles . I do a lot of shovels , been a semi pro hobby of mine forever . My garage shop is better stocked than most idies .

Try them and make a phone call their web site isn't the best but they are old school types who know the beast well .

 

You can go crazy trying to figure out what pistons to use. I've always used Weisco, S&S and KB for stock or near stock aps. There are companies out there who will make you pistons for custom/racing aps, like T&O. Proper break-in is what will give you longivity and reliability.
Remember; the advertised comp ratio is generally the best comp ratio that piston will deliver, after the cylinder and head are set up properly, clearanced and measured. Just slapping in a set of pistons on a stock motor will not get you that 9:1.
Nothing sounds better than a well tuned shovel with a healthy compression ratio.

 

I made the mistake of running Weisco 9.5 pistons in my 84 FX.
Compression too high for today's gas (or even mid-90's gas)
Thing pinged and rattled. It had a Mikuni-40 on it so I raised
the needle to fatten it up a hair. Knowing what I know now,
I'd have gone 8.5-1 and run the 485 cam instead of the 440.

Other probl was, when it was hot, the pissy little hitachi
starter wouldn't crank it over. Good thing she had a kicker
too.

 

I am running KB's in my EVO with no issues.You shouldn't have problems with them if this were done right.You really aren't breaking in the pistons anyway, its the rings that need to be seated.Today they do things abit different than in the shovel days.My break in went with heat cycles like initially starting and letting the engine get warm to the touch then shut her down and completely cool off.Do this three or four times.Then take it for a ride at low RPM's for 10-15 minutes let it cool.Do this three or four times and you should be good to go.Its all about the heat.My method may not be completely in line with all builders but it works.I think they are good pistons.

 

Just for conversation sake, higher compression does mean higher octane ratings. I found that when you jump into the 9.5:1 and higher, and have to run pump gas, it is probably better to go to a dual plug and single fire ignition setup. You get a much better burn.
I ran a 80" shovel with Weisco 9.5:1, and after the heads (S&S) were set up, I was running a 9.75:1; It had a Leinwebber L61, a Super D (gas) with twin ThunderJets, a Crane HI4 with dual plugs. From 3000 to 6500 rpm it would pull your arms out of socket. I ran Chevron 93. I know this is extreme, but you can use higher compression pistions on pump gas. You just have to set it up properly.

 

Agreed. I'd be the 1st to say mine wasn't set up properly.
But that was mid 90's Calif gas too w/MTBE.
So fuel was a big issue.
My dad ran 10-1's in the 74' Shovel in the 70's & 80's & never had
a problem.