difference between 175 and 200 crossflow

[wexrocks]

just curious on my '83 175 crossflow, what is the difference between this and a 200? I know the 235 has different port timing, comp., etc. I'm guessing it's not just carbs...

[Riverratt]

Not sure but I think I have a 200 block laying around if you are interested.

[rockman69]

I believe the 150/175 were same block, different carbs. 200 were different in porting,(same bore, exhaust) 235 different altogether....(bore, exhaust, etc.)

[wexrocks]

Not sure but I think I have a 200 block laying around if you are interested.

Riverratt, I'm afraid I can't get that out of your way for ya. I'm not up for swapping everything over to another block. I knew the 235's were a whole different animal as I was gathering info on here last year, but I was just thinking while I'm getting this motor ready for the season and had the carbs off anyway, if it wasn't too involved I'd bump it up, but aparently not so simple. Figures! I still might do what was discussed last year with 235 heads, 200 carbs, and stuffers, but the compression scares me with today's crap gas, and I wouldn't want to risk the motor trying to figure out jetting. I need it for the season, don't wanna be pulling pistons to start my year off.

[EMDSAPMGR]

Using the 79 as an example: The blocks are both 149 cubic inches flatback models. The 150/175 is a low port block. The 200 block is a high port block, as is evidenced by the higher factory operating rpm ranges. (The 200 runs the same rpm's as the 235.) The 200 uses the intake filler blocks that are in the 235-(not found in the 150/175.) The 200 carbs are more like the 235-they have and extra pullover jet similar to the 235 carbs and have 1 5/16" throats. The 150/175/200 all use the same heads. The 150/175/200 all use the same exhaust megaphone under the exhaust adaptrer. The 235 is different. All the engines use the same timing-28 degrees. The only difference between a 150 and a 175 is carbs. All of this should apply to the 83 model, except the 83 carbs are a newer style and all use the same 3 types of jets (low, mid and high.) Also, the 83 carbs have the nipples for the cold start primer solenoid hoses.

[wexrocks]

The '83 175 carbs do have the primer setup. They are also stamped 1 5/16. I am guessing the difference is the extra jet? I guess I am wondering if
anyone has put together the combo that was suggested to me of 200 carbs and 235 heads with the intake filler blocks, and have put some hours on them. Maybe this setup wouldn't go well with the low port block? This thing runs excellent and I would love some more power, just don't wanna risk blowing it...

[rockman69]

I did just about the exact thing youre thinking of doing. But started with an '80 150, added 235 carbs (1 3/8"), 235 heads (872/873), intake stuffers.... and 12 pnt. alloy head bolts that really made her perform! Very noticable increase in low and mid range pull. Never did a comp. check though.
I have extra stuffers if interested.
Ran like that for 2 seasons and then dismantled her to put on a shelf, and went with a v8 on a 21 talon. I was 10 when my father bought the 150 xflow so it has more sentimental value than anything, so itll be around a long time. It stuck a piston in 82 or 83, but ran like a top ever after.
Love my crossflow but the v8 has a little more grunt!

[EMDSAPMGR]

You can get those 1 3/8" carbs to work on your low port crossflow, but you will spend a lot of time rejetting the carbs. OMC did put some of these large carbs on the 150 XP/GT engines in the late 80's for a year so two. Personally, I don't think it's worth the time spent for the results. Those large carbs work better on the big bore 160 cube crossflows and the small bore 235's with the special exhaust system. You will be happy with just reusing your 83 3-jet 1 5/16" carbs. You can jet them up to run with any mods you may have planned. Keep in mind, the larger the carb throats, the worse the holeshot, but the better top end. My experience is similar to Rockmaster's. Starting with a 150 block, I added the 200 1 5/16" carbs, rubber intake stuffers and put on the 872/873 heads. When I had the engine down, I ported it (squared them off) and added a set of composite reeds. The stock 200 carbs overfueled somewhat, so I spent a few weekends on swapping/changing the high speed jets to smaller ones. The engine ran flawlessly and very strong. The porting picked up the rpm range on top end. The high compression heads compensated for the slight increase in port timing due to my porting. Depending on your mods it is possible that your final engine will run strong and reliably to 6000. Keep in mind, the original 582138 power packs were ulimited packs. They are not made anymore. If either pack was replaced on your engine over the years-it likely was with a newer (superceded) pack which is rev limited at 5800. A shame to waste good hp potential on a 5800 rev limit pack.

[rockman69]

Some good info to know here....

I never had problems with holeshot or top end. Never checked my plugs to see how shes burning (probably should have!) When the primer was pushed in at pretty much any speed, she bogged down immediately so, I assumed it was running pretty rich from the get go. When I put er on a smaller hull (next project is going to be a vector/viking!) I will pay more attention to jetting. Maybe change to the 1 5/16 carbs and see what happens.
also have all the fixin's for a 235 complete so, that may be next....

[wexrocks]

thanks for all the input and detailed info, very appreciated!

first guess off the top of my head, based on the different results you guys had (and again, just a shot in the dark here) I wonder if the smaller bore 200 carbs drew more fuel through the jets because of a the air coming through a tighter throat? just trying to determine where the rich issue came from. or maybe because Rockman wasn't reading the plugs, maybe both actually were a little rich, but just didn't present in actual running issues...? and I guess because carbs were the only difference between the 150/175, these results should hold true with mine.

I'm thinking I might try it... a few questions I would have would be, should I start somewhere half way between the 175 and 200 jet sizes? all, or just the high?

I'm guessing the 872/873 heads are the small bore 235's? are they each stamped 872/873, or is that a left/right part #?

and Rockman, I'll pm you about the stuffers...

thanks again guys! anybody else try this?

[EMDSAPMGR]

Yes, that's correct. You get faster airflow thru the smaller carb throat. The offset is that at high rpm's they won't flow as much air/fuel, so make a few less hp/rpm's. Re-using your existing carbs after powerhead upgrades, you will probably find the engine will run fairly well. Two strokes run great when running lean (not good) so your engine will probably run fine with existing jetting. I'd suggest you do a single test run with your stock mains (.057 jets.) Document your plug color, max rpm's and top speed. When at max rpm's push in on the key-the extra fuel may cause the engine to pickup rpm's, which indcates the engine is still lean. Then go up one jet size. Repeat till you are running just slightly rich-when you push in on the key at top end, it should slightly bog. You won't have to repeat your testing often as the 200's that year used .060 jets. It's easier compare results by going up in sizes than just pick higher number jets and try them. You need to plot your results so you can compare where you've been. You want to wind up with high speed jets slightly on the fat (rich) side. Your idle air bleeds and mid jets shouldn't need changing as they are already the same sizes as in the 200 carb. The heads are 323872/873.

[gmcgruther]

Not sure but I think I have a 200 block laying around if you are interested.

How much for the spare block? I;m interested, I need to know what year,GT OR XP, 200 OR 235?