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61 VBB 76 Rally 200 79 P200 80 Sport 100
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61 VBB 76 Rally 200 79 P200 80 Sport 100
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Location: Folsom CA
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My 79 P200 runs great...no hesitation or hunting on acceleration or when slowing....nice steady idle within specs when she's warm.

But the soot from the exhaust seems excessive and the MPGs is around 50-65, and the top speed won't hit 60 mph.

Am I being paranoid or are this signs I've got work to do? It would seem to me that the MPG should exceed 75-80and her top speed should be above 60 mph,
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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Is that near 60mph on the Speedo or on GPS? A perfectly working factory stock P200 should do 62mph on GPS, or approx 70mph on the vespa Speedo. Sitting up, on the flat, no wind.

Depending on oil and fuel used, they do block up over time. Carbon builds up in the exhaust port near the piston and slowly fills the exhaust box. The big fat piston rings run forever but only have peak performance for a much shorter time. The blocked exhaust is the sneakiest issue, changing for a known good one is the only way to be sure.
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When was the last time it had a decoke? Pop the cylinder head off to see what its looking like. Polish it up and as suggested inside the exhaust stub too. Decoke xhaust too or treat yourself to new road 2. Whats the air filter looking like, clean as scheduled. I've got a dr177 and 24mm with road and get about 80 mpg with 62 mph GPS. Yours should be good for that.
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61 VBB 76 Rally 200 79 P200 80 Sport 100
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61 VBB 76 Rally 200 79 P200 80 Sport 100
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Location: Folsom CA
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These are all great suggestions, but the top end was recently (200 miles ago) updated with a first-over cylinder and rebore; all the seals were replaced as well. I'm goig to switch out the oil tomorrow to check it for fuel.

If I go with replacing the exhaust, is there something I should consider aside from a stock replacement?
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If you want a bit more top end you could put on a sip road 2.0 box pipe. They are the same profile as what you got, not as quiet, not loud, but will allow you to rev on longer than the existing standard pipe you have got. So you will get the same torque (see chart) but can get higher revs and 1HP extra. The difference between my DR177 with a SIP Road 2 versus a polini box original is 5mph in favour of the road 2.0 and i think for your standard setup you will be more than surprised if you put one on. Relatively inexpensive and just a few main jets too, just to get your carb setup for the bit of extra power.
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
UTC quote
Popgunandy wrote:
These are all great suggestions, but the top end was recently (200 miles ago) updated with a first-over cylinder and rebore; all the seals were replaced as well. I'm goig to switch out the oil tomorrow to check it for fuel.

If I go with replacing the exhaust, is there something I should consider aside from a stock replacement?
At least this only leaves exhaust on the list. Anything but the original exhaust. If you're heavy get a Polini box. If not a Sip Road 3. If money no object there are many many good choices.
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Has anybody tried a road 3.0 on a standard P200? Be good to know the results. They claim 10 to 25% power increase but these are on kitted engines. How do they perform on a standard engine? What is their ground clearance like too? Looking at their pricing they are cheap enough. £108.00 in the UK, thats similar to the road 2.0 I do like my Road 2.0 but be interested in how a road 3.0 actually pans out with something that is a mild bolt on, a dr177, say. I see they give 36 month warranty too, thats pretty decent. I found the polinibox horrible at top end, road 2.0 far better, 5mph gps more, so if a favourable review comes back on the road 3.0 i would be tempted to get one.
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61 VBB 76 Rally 200 79 P200 80 Sport 100
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Location: Folsom CA
 
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61 VBB 76 Rally 200 79 P200 80 Sport 100
Joined: UTC
Posts: 288
Location: Folsom CA
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New exhaust is the way to go...one question I have whether I go BMG, SIP, or Polini: do I need to concern myself with any upjetting beyond the main jet? It has the stock 116, which I'd probably kick up to 120, but what about the other jetting components, particularly the idle jet?

I'm inclined to go with the BMG Bigbox Touring or the SIP Road 2.0 (cheapest upgrades available right now and in stock). I live in a hilly area and could use the power but I don't really go above 60 mph much. The SIP 3.0 seems superfluous to me.
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Ossessionato
1979 P150X, 1983 P200E, 1987 PK125XL Elestart, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
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If you want torque the Polini is better down low. You'll definitely need to upjet, usually only the main is fine...
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Molto Verboso
GL, PK, PE200 with hack, Sears Rust Badge
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Molto Verboso
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Location: Deep in the heart of Texas
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Re: MPG Question
Popgunandy wrote:
My 79 P200 runs great...no hesitation or hunting on acceleration or when slowing....nice steady idle within specs when she's warm.

But the soot from the exhaust seems excessive and the MPGs is around 50-65, and the top speed won't hit 60 mph.

Am I being paranoid or are this signs I've got work to do? It would seem to me that the MPG should exceed 75-80and her top speed should be above 60 mph,
Check your carb to see if it has the 109 main jet. If so, change the carb to the one with a 116 main jet. Should see an increase of around 5 mph.
If your carb has the 116 main jet, get a better exhaust.
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