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Need Porting and Squish Specs for 87 LT250R

9K views 23 replies 8 participants last post by  drag lt guy 
#1 ·
Anyone willing to list porting specs for both woods and dunes?

Degrees and duration for intake and exhaust?

What about channge in port height? (At least I can measure a change in port height to know about what was done)

Squish band size and angle? cc's of dome?

I want porting and head re-chambering but I would like to have some idea what I should be hearing from the local motorcycle mechanics. Here in Michigan they are charging $110-120 for either porting or head re- chambering.
 
#3 ·
I would spend the $140 and send it to flotek. cant beat the price or the quality IMO
 
#5 ·
experience is the key but software will point you in the right direction
their is more than just durations to look like angles of the port roof angles of the sides of the transfer ports directing flow
110-120$ for a port job sound way to cheep
and 110-120$ to cut a head high
a good port job will be around 300$ and around 50$ to cut the head
you will find you get what you pay for !
 
#9 ·
LOL a good port job a set of dart,profiler,big chief,514ex or brodix heads is around 3000$ I guess it all what you call good .... a good running big block is around 50K but that will have a true 1250-1260 hp natural on gas so i guess if your happy with the low performance cheep work... you get what you pay for
 
#10 ·
that would be one mighty stout big block to be naturally aspirated and run on pump gas. cant say that ive seen one of those yet, late models are around 850-900 and that is on alcohol and will set you back 45k. but back to the topic 110-130 dollars is way too much to rechamber a head.
 
#11 ·
yea that is way to much i would say $40-$60 is what it should cost.
 
#12 · (Edited)
OK enough with the big block 4 stroke BS.

Yes $300 for just a port job is way too much for me. If that was the going rate, I would not even be talking about this. And I agree the shops are over-charging for the head to be cut. I have used a CNC lathe and could actually cut it myself if I had some #'s, angles, and volumes, and well a CNC lathe with tools.

The shop I decided on has TSR software and builds lots of motors.

I looked at Dr. Q's site and found no pricing for his work. I did find some of his comments alluding to in my opinion eviltwin to be....well.... competitive.

What I did find on the Dr Q site was his comment to run the 85-86 LT head gasket then shim the base gasket. Which is an old trick to raise the ports with no work. Anybody know if the 85-86 LT head gasket is thinner and can be run on the 87-92 LT head/cylinder? Anyone ever shim or double up their base gaskets to raise the ports (my 86 Tecate looks to have 2 base gaskets)? Or does anyone know who will make the custom gaskets for the LT?
 
#13 ·
yea DR.Q had some choice words about a few people on here. He really seemed to LOVE denny though.
 
#14 · (Edited)
Everyone has an opinion. I think they both know more than I do about modding the LT. But I don't think they will give away any of their secrets for free. Don't blame them really.

I am just trying to get an idea of what I should be hearing from the mechanic. But you really never know until you try it.
 
#15 ·
I personally have never had good luck with double gaskets on anything at all. Maybe just a thicker gasket. I think that you will be hard pressed to get any #'s out of any one who does port work, becuase this is there primary source of income for most of them. the answer you will prolly get is that it takes alot of expierence and alot of trial and error.
 
#16 ·
The whole porting subject and engine design goes way beyond some #'s. It is all about matching the pipe shape, reeds, reed cage shape, head cut, carb and so on with the ports to make power over a certain rpm range so the hit is where you want it hence midrange (woods/mx) vs high rev (dune).

There is no straight forward answer and I understand that.
 
#17 ·
yeap, they gotta make a living so i doubt you get any answers. If you are tight on a budget try and find a local shop to port your motor that actually knows what they are doing. Denny is the cheapest I have found so far for motor work besides Jeff Mellot (local guy and a friend of the family) but he's a banshee guy really. Well if your super tight on money buy some porting tools and a good right angle porting tool and DO A LOT OF READING on porting. go to macdizzy.com and other sites that will give you the basic idea of how to port a motor.
 
#19 ·
HP numbers are only relative to how you are measuring it from before to after. I don't think there is a good answer to that. I saw an article say a 310 TRX owned by Duncan only made 50 HP. The Dr. Q website said a fully modded LT 270 might make low 50s HP but the clutch and trans don't hold up well.

Anyway I think the motor can make 30 HP with not much work and I would hope you could get 40-45 HP with porting/head cut/pipe/carb/reeds/no airbox/flywheel/stator/coil. I don't expect my motor to ever see 50 HP.
 
#20 ·
well theres honda 250rs on planet sand i n the dyno section that have broke the 50 rear wheel horse barrier with a ported stock cylinder ,it requires the right mods and it isnt an eas y feat ,most of the big name universal porting wont probably get yo u there though ..but the lt250 has the same potential .as far as the porting business and whatnot it is surely a very competative market in my experiance youll find alot of builders tend to discredit other builders only to bolster their own agenda/sales and there are cheaper priced engine builders than myself out there ..despite the fact i have probably 100 + actual detailed photos of my work online video and dyno runs compared to only what is touted by the shop owner or maybe a handful of their past customers .. just talk ...yet im told my ability is equated to a 11 year old useing a hammer and chisel like captain caveman lol i guess id rather let someone else say good things about me than ruin somebody elses reputation and sling shit .



 
#21 ·
It has been done where a stock cylinder 250r with a stroker crank and the right set up can make 70hp. probably on a rare ocasion that i happens though. I would say that a "Fully Modded" Lt250r could make around 60-65hp. But the most you are going to get out of a still rideable LT that isnt just for drag racing is I would say probably low to mid 50's. It has been done before that a Lt250r has made in the 60's hp. I would really like to be the first person to break high 60's :)
 
#22 ·
yet im told my ability is equated to a 11 year old useing a hammer and chisel like captain caveman lol
:laugh4: :laugh1: ahah man thats great. I dont think i buy into it after racing with Only2strokes blaster for a whole year.
 
#23 ·
First, A big amen on the shit slinging. we are a small enough group as it is. Second, I was more wanting to know seat of the pants feel. since I purchased my '89 I have upgraded pipe reeds topend axle tires rims and a 39mm pwk that I have about dialed in. I'm just wondering if a port job will make me smile like the pipe or more like the reeds???
 
#24 ·
are you currently impressed with the way it pulls? if you think its fast now, get a good port job on it and you might do more than smile. you may have to buy your self another pair of undwear
 
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