Porting practice: 371 xtorq

[Ronie]

I'm continuing on with my porting practice and today I started on a 372 xtorq cylinder. I've pretty much finished the cylinder, I'm just going to smooth everything out a little more. The plan is to put it on my 371. So far I've opened the exhaust to a little over 65% of the bore, Widened the floor of the intake aprox 1mm on each side and tapered it to the top. Where the intake boot connects ,I've tapered the roof downwards. The lower transfers have been gasket matched and the cylinder flange has been cut down so it fits the 371 case and it's been removed at the transfers. I'm going to remove the dividers in the intake boot and in the plastic piece that the filter goes on. I don't have a xtroq carb so I'm going to try a 385 carb and see how it does. The numbers are, exhaust 101, transfers 121 and intake is 78. Squish is .020. I haven't heard of anyone using a 385 carb or removing the skirt at the lower transfers, hopefully it works out. Constructive criticism is always appreciated.

 

[Ronie]

Bad news, I got it together, put the plug in it and it's stripped. So I'll be putting this aside for now and fix the plug hole some time in the future.

 

[huskyboy]

Leave the strato alone, they run nicer with it intact in my experiences. Match the lowers to the base using the gasket. They are pretty far off.

 

[Yotaismygame]

Bad news, I got it together, put the plug in it and it's stripped. So I'll be putting this aside for now and fix the plug hole some time in the future.

Buy the correct insert with swag tool. Its very easy to fix, and you'll never know it was there. Something like this.

 

[Ronie]

Buy the correct insert with swag tool. Its very easy to fix, and you'll never know it was there. Something like this.View attachment 182364

I have one of those kits. The problem is that it's had a heli coil or insert in it before and it stripped. The hole is now to big for one of those kits to work. They do make over sized inserts and I may go that route or I could have an aluminum bung welded in. In any case I'm not in a rush, I just finisher up porting an oe 372 cylinder to put on my 371. Thanks for the tip and congratulations on getting a lathe. Here's the one going on it. Nothing extreme, I did it just like the 365 cylinder I posted on here last month.

 

[srcarr52]

I have one of those kits. The problem is that it's had a heli coil or insert in it before and it stripped. The hole is now to big for one of those kits to work. They do make over sized inserts and I may go that route or I could have an aluminum bung welded in. In any case I'm not in a rush, I just finisher up porting an oe 372 cylinder to put on my 371. Thanks for the tip and congratulations on getting a lathe. Here's the one going on it. Nothing extreme, I did it just like the 365 cylinder I posted on here last month.

I weld the stripped hole shut and drill and tap a new hole. I probably fix 20 a year.

 

[Ronie]

I weld the stripped hole shut and drill and tap a new hole. I probably fix 20 a year.

That's a good Idea too.

 

[Ronie]

Just an update on that 371. I ended up porting an oe 372 cylinder and it turned out pretty good. It won't win any races but I think it's stronger and faster than a stock saw.

 

[cuinrearview]

Sounds fast in the cut man.

 

[Ronie]

Sounds fast in the cut man.

That's the saw I showed you last May but it was tuned rich, around 13,200. I got it tuned a little over 14,000 wot now and it really woke up. It ran ok before but I had better running saws so I took the carb for another saw and put it on the shelf until yesterday. I'm glade I pulled it down and put a carb on it now. It's running good enough now that I think it needs some oem plastics put on it, I've got some new ones I've been saving.

Video of it at 13,200

 

[huskyboy]

Wait till she seats the rings and frees up... but it already looks pretty nice

 

[David Young]

if you try to put the xt jug on an xp saw case it will pinch the jug extensions and choke the bore. If you have to do it make sure you clearance the case or the extensions.

 

[Ronie]

if you try to put the xt jug on an xp saw case it will pinch the jug extensions and choke the bore. If you have to do it make sure you clearance the case or the extensions.

That's true, I cut down the flange on the xt cylinder.